I think people on this site (not just in here, just in general) have an absolutely ridiculous idea for what a "rebuild" actually looks like. Even the most aggressive rebuilds like the Rangers sold off pieces gradually. The Rangers rebuild started at the 2018 deadline, but they didn't nuke the team all at once. The Rangers rebuild was really aggressive, but it still took 3 deadlines and they mostly only traded rentals. The idea that a team would just nuke itself to orbit to completely bottom out is just not how teams operate.
But anyways, how this relates to Dubas is that he is not trying to push Crosby and Malkin out of Pittsburgh with a "rebuild" and it's a silly suggestion. At the same time, I do think Dubas thinks their window is closed and wants to rebuild/retool the team. If the players and coaches are mad about that, maybe they should look in the mirror and realize why Dubas thinks this team is toast. He added Erik Karlsson in the off-season and this team somehow got worse. I put that FAR more on coaching than I do on the players, but the players aren't innocent there.
The "rebuild" Dubas is going to do is keep the big guns while gradually selling off other pieces as their contracts expire. They'll do the same exact rebuild that every other team does, and will eventually truly bottom out once Crosby and Malkin retire. If Sullivan or the players are mad about that, maybe they should have shown Dubas more this year to make him think this team wasn't completely spent.