Are you doing all those at once? And are you doing any of those for a living or just a hobby?
I'd say that you might benefit from 16GB but still probably don't need as much as 32GB. In any case, getting 16GB(2x8GB) at first won't hurt. If you notice that things are running slow, get 2x8GB more and you'll have 32GB.
What the hell does it matter to you if he wants to max the ram out, it's cheap to do and not difficult either? I run a Windows VM and like to give it a full 12GB on my machine, and also running LR with huge catalogs, ripping BDs, have 20 web pages open all at the same time, etc. I have frequently chewed up a full 32GB and I'm not doing anything "professional".
It's like you're stalking this guy because he's spending money on something that "you" don't think "he needs".... for all you know he could have money flying like monkeys out of his butt.