My dear, first of all, no need to apologize for long posts or any kind of question. We are here to help and are glad to do it because we all love birds.
Now, thank you so very much for rescuing the poor dear thing! As you said, what kind of a monster would throw away a living being in the trash?!
As to your problem. Yes, he is afraid of you because you grabbed him. I am not blaming you for it, you had to do it in order to clean his filthy cage properly. I am simply telling you what the problem is. As to whether he will bond with you or your wife, it's up to him. It is entirely possible that he bonds with your wife because she was not the one to grab him and also because she is there all the time BUT it doesn't necessarily have to be so. I have a bird (Isis, female African Red Bellied Parrot) that has always adored my husband even though he used to be away working for days and days at a time (sometimes, up to ten days). It took me a couple of years to get her to be my friend but my husband was, is and always will be her chosen one and nothing I can do or say will change this. This particularity of parrots comes from the fact that they have only one mate and that they keep it all their lives and that is why companion parrots (monks or quakers are companion parrots), are always one-person birds. But just because they prefer one person it does not mean that they cannot be friendly with other people. Isis is OK with me, she is not afraid of me, does not bite me, steps up to a stick for me with no problem and, every single evening, when I feed her dinner, she asks me to scratch her head for a while and does not eat her dinner until I do. My own quaker, Keku (a turquoise female), loves me most of all but she would step up for my husband, takes treats from his hand and even perch on his shoulders for a little while.
How to make him like you... Well, it's going to take time. Not only because of what you did but because everything with parrots takes time. It's the way they are. So be patient, consistent and persistent in your interactions with him and it will happen.
The best way to win them over is not to ask them for anything but spend as much time as you can with him in the same room. Talk, sing, whistle to him without staring and always in a casual, nonchalant way (nothing reassures a prey animal more than not really paying attention to it). You need to make him understand that there is nothing for him to fear about you and that you want to be his friend. Offer him a treat every now and then (take the millet spray out of his cage because you need to use protein food as a reward or treat) but, if he doesn't take it from your fingers, just leave it where he can reach it and walk away - this is a gift you are giving him, a way to show him you want to be his friend. If you don't free-feed protein food and only use it for dinner (which is the right way of feeding them), you can let him out of his cage about two hours before sunset and, one hour before, put the food in his cage - it might take a couple of days but he will go back in on its own. I have a GCC (green cheek conure) that was parent-raised (meaning, it was not hand-fed by humans when a baby so she never imprinted to humans and does not consider them part of her family) and, most likely, kept in not too good condition (she was all plucked and VERY high strung) but she still comes out to fly every day and goes back into her cage on her own - sometimes we have to wait a bit for her to do it (she is VERY smart and tries to steal food real quick and come out of her cage again
) but she does it every day - and has even learned what "Go Home!" means (I use that phrase to tell them to go back to their cages).
As time goes by and he starts feeling better (I am sure he is still not feeling 100% because it takes up to two years of good food to get them back to where they should be after bad care) and stronger, and he sees that you only want to be good to him, he will start trusting you and, when it comes to parrots, there is a very short step from trust to love because they are naturally VERY affectionate animals.
One more thing, make sure he is kept at a strict solar schedule with two hours of dawn and dusk because quakers are not tropical birds, they come from temperate climate countries (I was born and raised in one of them, in South America) and are VERY sensitive to the solar schedule. If you don't, he will be overly hormonal and that means chronic pain, frustration and aggression.
Just one more thing to prove to you that parrots do bond deeply with their new owners. I got my Keku when she was already 4 and half years old and she was given up because she screamed too much but she never screams here, she has learned lots of words and phrases (she never learned a single word with her previous owners) and she is the most loving little thing! In the evening, when I go around all the cages telling them Good Night, when I come to her cage, she is usually all the way in the back but, as soon as she hears me saying: "Where's my sweet baby bird? Come here and give me a kiss" (she knows what 'give me a kiss' means as well as 'sweet baby bird' because she says these things herself
), she comes over and sticks her beak out between the bars to kiss me (and, of course, she melts my heart every time - I love that little bird with a passion!). So, keep at it and be patient and you will have a very loving friend for a long time.