Sounds like a real pr*ck to me.
Any number of pro bands use modelling, so that's a non-starter. Congrats on him seeing a mic at a Van Halen gig, he's evidently very proud of that, but the fact is that with Fractal, Kemper and L6 all making such killer products it's much easier to fly a modeller around the globe than a stack. If they weren't up to the task, they wouldn't get used.
If the problem is monitoring . . . what exactly is a super-pro setup? If you have any monitoring at all then there's no problem - I've played plenty of shows like that, and it's fine. In fact, without competing stage volumes it makes managing onstage monitoring a lot easier.
Are you going to have a great soundguy at every show, who will use the same mic in the exact same position? Will you ever share cabs? If not, then there's no consistency in your sound. Helix can give you this - you'll always have the exact same tone, every single gig you do.
Why simulate a Marshall? Well, aside from the beauty of not having to carry the f*cking thing around everywhere, you can instantly switch it to a Fender, or a Matchless . . . and you can adjust any part of it at any point.
Not a leg to stand on, just wants to make out like he knows more than you.