That’s a good idea pedo but you will still get screwed if he decides to jump over you and falcon kick. you’re still 4 frames behind since a blocked low dive kick is +7 and jump take off is 3. FAlcon kick start up is 11 but if he starts up over your head i don’t think a c. fierce’s hitbox will be able to touch him. in that cas eyou are probably better off using st. rh cause it’s 4 frame start up and way better hitbox.
EDIT: or scarlet terror which will take care of any sort of dive kick after a blocked dive kick since +7 still won’t cover his ass against a 4 frame start up considering another dive kick would be 3 frame take off + 11 frame start up = 14 frames meaning 14-7=7 frames you have to defend which leaves a 2 frame window for c. fp, 3 frame for st. hk and i think the reversal window is like 5 frames now or something? so big window to reversal ST and i mean i’m pretty sure if he were to neutral jump he might be able to beat you if he does his neutral jump move as soon as possible but any dive kick is beaten or lands behind you and you’re probably safe.
So if you think he’s gonna dive kick you should probably just ST. More damage, knockdown, less likely to lose than c. fp, easier to hit him with since it’s hitbox is so much bigger. c. FP has only 6 frames less recovery so you’re still probably less likely to get screwed doing ST because c. FP also doesn’t move you out of the way if he jumps over you, or beat his neutral jump since he’ll probably be out of the way. c. FP is also -11 on block which is worse than ST but you have the benefit of not being as likely to be punished because of the distance created. Rufus can reversal EX Galactic and reversal U2 that so it still isn’t safe. ST all the way, c. FP has hardly any redeeming qualities. in terms of preventing people from jumping out it’s better than HK ST but c. fp is still worse than st. HK when it comes to that. IMO c. fp is strictly relegated to an even more situational anti-air than everything else vega has and as a good combo finisher from st. lk, c. mk and cl. fp from certain distances that st. hk won’t get both hits on. Although st. HK will actually hit most crouchers unlike c. fp even though it forces stand.