you can instant block a burst, but that leaves it only at -1
if you air ib it leaves you at -6, which you still can't really punish, unless your close enough to the ground that you recover instantly and do your 6 frame 2A
but i don't think thats even possible.
carl litchi and ragna can technically punish it in the air (carl's ja/litchi air hatsu/air id)
ALL of the above is for gold burst ^
if you ib a green burst, dash up and do a normal that isn't 2C