If he follows on the last Kwaremont, he likely goes with Pog to the finish and wins the sprint. His best chance to win here, if he himself is not strong enough to drop Pog.I mean yeah, that'd be the only reasonable tactics for him, but still I think he'd be dropped by Pogacar.
Also, another thing is that van der Poel was feeling quite confident coming to the race (after MSR win; I know it's totally different race, but still) and after the first climbs, where he clearly felt good. And passive racing is certainly not his instinct.
He didnt, so he lost and likely would have lost against Visma/Trek trying to play tactical games. As they had a number of riders that were good today. He would have had to close multiple gaps and had to chase.
If Pog not here, MVDP would have attacked to drop the others.
With Pog here, he knows he has to follow and will work to keep the others behind. So it is just him vs Pog. He sees that as his best chance to win rather than relying on others or risking being tactically outplayed. MVDP raced to win.
In no scenario, with or without Pog, would he like to have Van Aert or Pedersen with him going into a sprint.