I don't think SSDs are good for gaming machines. Unless, of course, he doesn't mind deleting games and keeping only the few ones he's playing at the moment. Loading times are pretty fast even on HDDs and you can get a lot of space without a lot of cost (4 TB here).
Even on my PS3 I had to resort to a 500 GB HDD. Current gen games are huge. Most games are more than 30 GB now, so it won't cut.
If he has a pretty fast internet, if he won't usually play games that he already complete or if he won't want to keep more than 10 games installed all the time (which is normal if he plays online at least), then it can be a good deal.
SSDs are still really useful to have your OS and programs on it.
I own a laptop, when I bought a mSATA SSD to put my OS and apps on it, my laptop went Super Sayan. I'm never going back to HDD only.
But weirdly enough, for games it's not really different.