Yes, teams can pull QOs at any time. And players can sign QOs at any time. Once signed, I would not think so.
Which led me to that assumption in the other thread (re: next steps) and we’ve placed ourselves in; or been placed in some sort of quarantine right now w/ the league until … (not sure what that might be - internal investigation or league security investigation). E.g. I wonder if any FA or trade will go into or out of Charlotte right now. I could be completely wrong.