While I'm thankful for your efforts to correct this criminal activity, I do think you should remove one part from your warning.
Secondly, the exchanges can power up their Steem and elect new witnesses to reverse HF23.
If by this you mean help themselves to private Steem as they did once before in aiding Justin Sun in the takeover, that is a big no no. I'm shocked they seem to have gotten away with it virtually unscathed the first time. If they do it again, the negative ripples throughout the world of crypto will simply deepen. Bad enough they showed they were willing to do this once. Worse that Justin shows a chain can just empty ones wallet out at will. If they once again help themselves at the exchanges to their users assets, it will once again affirm only an idiot will participate in crypto with so many masters just willing to help themselves to your property.
Normally I would agree and this is a last resort if the first two options fail (Bittrex returns funds or pressure gets HF23 reversed).
But although it is distasteful and potentially a breach of civil law obligations to users for exchanges to use user funds to intervene in governance, when it is to return stolen property it is a legal obligation under criminal law that over-rides other concerns.