I could be misunderstanding, but this sounds like it would be a wash sale, which would prevent the seller from claiming the loss on their taxes.

https://www.investopedia.com/terms/w/washsale.asp

I would simply hold it until the value goes to zero. In the event enterprise value doesn’t go to zero, I would gift any gains back to OP after taxes (because I’m trying to do them a favor, not make an investment).