Why not 2. ... c6 after English Opening, Jaenisch Gambit Accepted (1. c4 b5 2. cxb5 c6)?

I cannot find any discussion of this second move for Black.  It reminds me of the Danish Gambit and the Smith-Morra Gambit as White.

The fact that there are articles and videos on the Jaenisch Gambit versus the English, and they consider multiple second moves by  Black, but NONE of them discuss 2. ... c6, makes me thing there is something unsound about it that is obvious, just not obvious to me.

I mean, unsound beyond merely not getting enough compensation for the gambit pawn.  I am pretty convinced from what I've read that there is technically not enough compensation for the pawns given up in the Danish Gambit opening, but I still do well with it as an offbeat and aggressive and tactical opening.   The fact no one even talks about 2. ... c6 makes me think there is a bigger problem with this move, like it creates some immediate tactical or positional weakness I'm not perceiving.

Anyone have thoughts on this?

There is a line in the Nimzo-Indian where black does something very similar.