The law has been around long enough to contain provisions against such (very old) trickery and shenanigans.
I don't see JPM or anyone else being stupid enough to attempt anything like this. A tender offer for the shares of a debtor in reorg that the debtor is currently representing (in the POR) as worthless? Why would anyone make such an offer unless it were because they had access to non-public information (that the shares were not worthless), and that would open a whole new can of worms.