NRS isn't known for having reliable visible hitboxes. Biggest example is projectiles. How many projectiles have you seen that you could have sworn you could jump over easily in any other fighter, but in NRS games you'll get hit almost every time.
Regardless back to subby-z, I'm hesitant to even give him a fix like this. Not because of how he struggles against top tiers, but because of how he dominates a good portion of the cast while barely trying.
Sure Sub-Zero cannot win by playing keep away alone, but he can put up an ice clone, shoot some iceballs, throw the clone, or shatter the clone, and quickly put up another one, and repeat the process until he has considerable amounts of meter. And can make throwing counter projectiles risky because of EX ice ball or a possible trade. Some characters simply do not have the tools to deal with this. Which is why I consider Sub-Zero to be one of the most unbalanced characters in the game.
And yes while I may not be an expert with the character, I have played him quite a bit, and he was actually my main character. Though I switched to Cryomancer because I didn't enjoy sitting behind the ice clone and letting it kill my opponent for me. Still not a fan of the style but it at least has some more thought behind it now. Due to people leveling up, and the going away on block nerf. And yes I do, do much better with Grandmaster.
But I'll say this, if they fix the clone not freezing when Sub-Zero blocks, which will allow Subby-Z to bully the cast who have trouble against it which is probably half. Then I suggest that they buff that half's options. For Example Kitana get's a measly 14% for a bar of meter if she gets the read, and it's highly unsafe if she doesn't. Sonya as retarded as her mix ups are gets hardly anything as well. Reptile hardly gets a punish, same for Kano, Cassie, Johnny, Liu Kang, you could throw Sub-Zero himself in there as well.
I know you are salty at the nerf, but Sub-Zero isn't what many would consider a "bad" character, in fact he is very good. People have pointed this out, that even without the clone "threat" he has excellent normals, and good mix ups. Both on the ground and in the air. His slide lets him zip under other zoners projectiles, and practically has no recovery when it whiffs. It's also a constant threat stuck in the back of players minds, just knowing that you could do a fast moving low, and while it's super punishable, it leaves them open to overheads. That frankly while is punishable is still tough to punish for a majority of the cast, or has extremely strict timing, which in the heat of a match would make it less likely to happen.
So yes, if they fix this, I'd like to see weaker characters also get more buffs, not just to deal with Sub-Zero but to deal with other top tier characters that you, yourself complain about and compare to Sub-Zero.