I was going to give my son a system, with brand new Solid Steel rack but he has AirPods???

What, did I take a wrong turn and end up in the "Ask Amy" blog? :)
No, it's the age-old situation of buying something for someone that they didn't want, which usually means you 1.) didn't pay enough attention to their preferences and/or 2.) you're trying to "improve" them by forcing your ideals upon them.  Example: "I bought you this book on how to organize your life - I think it might do you good".  My suggestion is to get rid of anything you have that you've offered to him that he didn't want, because if you keep those things around you will only be reminded every time you see them that he "rejected" your gift.  People do change, but they need to get there on their own.  I've tried to get my daughter to listen to my system to see how much better it sounds than her cheap Apple earbuds (actually bought her some Tin Hifi IEM's to get closer to better sound) and she'll listen the appropriate amount of time to not hurt my feelings, but it's clear she's not interested.

I went through this with two of my kids about a decade ago.  As they got their own places I showed up with good used equipment that I had carefully shopped for, or in some cases handed down.  After setting everything up they both dismantled it and gave it away or threw it out.  Ironically one of them did want something better recently for their TV and Video gaming so they took an AVR off my hands and I happily replaced it with an Anthem AVR with ARC.  Different Generation, Different Priorities 

I have two sons.  One lives in CA the other about 10 minutes from my house here in MD.  I have a ton of vintage gear that I've been giving away to family and god children, and had planned to buy each of my sons a decent 2-channel system. 

My CA son wanted money instead, which is fine.  I sent him a check.

My MD son wanted some of my vintage gear because that's what he grew up with, and he's really into music (as I am).  I gave him a Pioneer SPEC-4 power amp, Rodec mixer, Soundcraftsman EQ/Pre, Technics SL-1600 MK2 TT, McIntosh CD player, McIntosh Tuner, and DCM TimeWindow 3 speakers.  I offered him a complete McIntosh stack but he didn't want the McIntosh MC-2600 power amp or McIntosh 31v preamp/controller.  I'm OK with it because I'm just trying to downsize. 

Here's the deal you've a hobby, a sound system, maybe extra equipment. Your kid's probably grew up in your house and likely were exposed to hearing and all involved. The key word is they grew up, and developed their own way of thinking wants and needs, bingo you've done your job.
We can't expect the dumping of unwanted or unvalued junk on them to be accepted. Attempt the turn over if excepted fine if not there's always ebay...
Move on.