They say Sieg is best when you play with balls to the wall guessing. Big risks, big reward. Weaknesses don't matter if your opponent died to three 3(B)s.
Ironically the only counter is to get up in there and do the same, assuming the Sieg is no slouch wearing you down at range correctly. The annoying part is, if you're playing an unknown, you may not have time to determine if indeed he 'knows what he's doing'. You could lose a round for it. Maybe two.
Do not ever use simplistic shutdown moves, because 2A gets hard countered, of course. However, the 2K applies and severely controls tempo, as we saw from innovators in other lands early on with the game.
If you can throw him, he sucks.
That's all I know. OTOH, if anyone knows reliable ways to snuff stance roulette, then you are basically unapproachable because you can wall up and just arbitrarily 22B him. BB becomes relatively sane against his speed.