Let me start with 2 things: first is that Zangief is a lot more weaker than in ST version and most players (even the ones that play ST at high level) will agree with this fact, and second is that Zangief CCs are weak and not strong like you are saying.
Now let me post FACTS that can prove why Zangief CCs ARE weak:
If you really play Alpha 2 then you know that Deadly CC Zones (Valle CCs) are one of the most powerfull weapons in this game and Zangief does not have a Deadly CC like some characters, heres a perfect example:
In order to a character have a Deadly CC Zone (Valle CC) this character needs to have a move that once is activated theres no way to fight it or block it once the character is standing, and how this is done you may ask? —> Deadly CC Zone (Valle CC) is so amazing powerfull because once it is activated on the CC Zone and once the character is standing theres nothing he can do to stop for been hited for a massive fast combo, and this is simple because (for example: Ryu) can start his CC with c.HK into any other move that he wantsso fast that his opponent will not have time to react once hes into the CC Zone.
Zangief does NOT have Deadly CC Zone like Ryu (note that Im not saying that Zangief does have have a powerfull CC, its not that, Zangief can have a powerfull CC but he DOES NOT have a Dealy CC Zone) and some people maybe asking why is that? —> just because Zangief c.HK takes a few more frames than Ryu c.HK to hit the opponent on CC mode and those very few frames will be the diference between “Deadly” and "Powerfull"
So I agree when you said that Zangief has a powerfull CC, yes… thats true, Zangief does really have a powerfull CC but its not a Deadly CC and that is a big diference when playing against characters like Chun Li.
Also: the famous knee drop into spd, splash into spd will not be as good like in ST and you know why, right? both knee drop and splash or any other air attack can be stoped very easy due to 2 reasons: first because his air attacks dont have that big priority like in ST and second because if he does that against a good anti air (example: Ken LP DP that has a huge priority against air attacks) he will go down again.
I could post that Zangief is a lot more weaker and you could post that Zangief is stronger or with the same power of Super Turbo version but that will not change much because if we dont play against each other then all we can do is to post what we know of each character in this game.