As for making b2 7% damage instead of 9%, currently Sub Zero can get a 38% combo in the corner off a raw overhead without the use of a clone shatter or meter, 36% if you want the safe clone setup. That's too much considering how high tier he is with his armor breaking tech. Not even Warlock Quan Chi can get that much damage off his overhead for a bar.
Actually Warlock gets between 40-45% for a bar off a faster and safer overhead which can go into pressure on block if you ex the rune
Lastly, b2 from behind the clone in the corner might not be completely safe, but it requires a 12 frame or faster forward advancing EX reversal attack to punish it, which few characters have, and even if they do have it, unless it's a launcher it's not really worth it.
Heres the list of characters with at least one non-poke PUNISH for a blocked B2 from behind the Clone, using "tom bradys" spacing tech. FTR I hate calling it Tom Brady's but I'm doing it here just so that we are all on the same page with what I'm referring to
Lao
Jax
Sonya
Kenshi
Kitana
Scorpion
Sub-Zero
Jacqui
Kung Jin
Tanya
Shinnok
Kano
Johnny Cage
Erron Black
Reptile
Quan Chi
Ermac
Ferra Torr
DVorah
Raiden
Heres a list of the characters that can't
Mileena (gets a JiP into whatever she wants which is a mix-up so gets something at least)
Takeda (goes straight into his really strong pressure game tho)
Cassie (makes up for it by being able to armor through everything Sub does without getting broken by anything, a worthwhile trade, shes probably better off than everyone else in fact so doesn't really count)
Liu Kang (although the frame data indicated that ex-iAFB might do it, I don't have the skills to check tho so we'll put this in here)
Predator (gets a D4 so gets out of the corner and fully gets his game started at least, but I did specify no pokes so I'll give you this one)
untested characters:
Goro
Jason
Kotal
The first two I don't own, the second one I did test but I can't for the life of me remember if I could punish it or not (i just tested entire cast this one is a little fuzzy) if he does have one it was a little abstract and hard execution so call it a no AFAIK
Basically almost every character in the game punishes B2 WITH clone out