Any smoke bomb following a blocked string is not playing smart.
It has around 10f recovery. your fastest poke is 6f or so, that means that after blocking a smoke bomb any move that is ~15f (correct me if my frame-maths failed) is going to be a free punish on you if you try to poke after, and anything faster than about 10f is going to hit you regardless, whether you block or not.
After some moves from the right spacing you can be a little more safe if your opponent has dinosaur arm normals, but theres no logic in doing something unsafe to make your opponents respect it. If its unsafe, and they are blocking, they NEVER have to respect it.
Thats like Kung Lao doing spins in peoples face, or raiden doing supermans in blockstrings, just so they know its there.
Off blocked strings the best thing you can do is hit confirm into a drift on block, and only smoke bomb when you get the hit.
I know i might sound a bit rude and harsh, but there is NO logic in what you are saying. You dont use punishable moves on blocking opponents regardless. You can risk it sure, a few months ago people didnt even think it was punishable, and were using smoke bomb xx d1 on block as a trap/blockstring. Now we know better, and i can surely say myself that i have been punished enough for it to take it out of my playstyle . Learn what spacing smoke bomb become unsafe, and dont throw smoke bombs there.