Whizbang Dustyboots
Gnometown Hero
If he would prefer a more old school style of play, this is a golden era for games with those vibes, although they're not produced by WotC.We're both pretty new to 5e, and haven't played it much yet. Life happened... He doesn't even have Tasha's. I think it's just a bit of crusty old coot of a 1/2e DM throwing a fit over 3 editions worth of accumulated changes. (He's my best friend since high school- I can say that, lol) And the modern outlook on how things should be done/ balanced, etc.
In particular, I recommend checking out the Shadowdark quickstart rules, which are free. Shadowdark has both an old school mentality and many of the benefits of modern play. It's also effectively impossible to optimize/min-max.