...bxa4?, will you damage your own quenside structure? No way! ...b4 is better. Then develop your pieces, and have a good position. You can play Bb7 too if you like to play the Marshall, though it is so risky, unlike the Marshall, so b4 is better. That anti-Marshall
The Anti-Marshall Variation- does it work?!

After b4 black can still try to play like in the marshall with d5
He can of course, if he is a fool.

In my forum about the scotch, someone says the Marshall can be defended with accurate play, someone who favors the ruy lopez. So if someone doesn't do an anti-marshall... what's the best line for white? Also, I agree you shouldn't go around calling fellow GMs fools... they could beat you in a game, then whos the fool?

After b4 black can still try to play like in the marshall with d5
He can of course, if he is a fool.
So you're basically saying that GM Laurent Fressinet is a fool? Interesting...
Fressinet played a single internet blitz game with 8.a4 b4 9.c3?! d5 some 14 years ago, but I doubt 9.c3 will come back as a serious option anytime soon (although it does have a couple of interesting ideas compared to a normal Marshall).
When I play black against ruy lopez, I faced the Anti-Marshall variation-but still got to play the Marshall Attack anyway!! Did my opponent do something wrong, or does a5 work in the first place? By the way, this was a bullet game, 2 minutes 1 sec increment. If me or my opponent messes up, it could be because of time pressure.
Thanks for any input!