He's certainly being abrasive, but he has a point.
The game is growing, and so there's more greenbeards than ever. I have no problem coaching them on the ways of the dwarf when I feel up to it, but sometimes I just want to host a high hazard mission and have a normal game. And there's no way to stop brand new players from joining, promptly getting destroyed, and then most likely quitting (hopefully just the match and not the game itself)... other than pre-emptively kicking them which is not what I'd consider ideal.
If we can't get the choice to add a (low, say about level 10) minimum requirement to join our haz4+ lobbies, then the game should at least do a better job of warning newbies that the hazard levels are a really big deal.
I know you don't want newbies to feel alienated by the locked games, but getting massacred in haz4 is also a bad experience for them. And for us, for what it's worth.