I don't really think it's like that. I think he is just a very loyal person and good teammate. He has been in the same relationship basically forever, been in the same team from the beginning, signed with long term bike manufacturer Canyon for life. Becoming famous or successful hasn't seemed to have changed MvdP at all.
When Philipsen radio'ed him once MvdP had closed down Pogacar on the Poggio that he had good legs and he should please wait, MvdP did not hesitate to work for him for a second. He was away with Pogacar (small gap only) and would have won the two up sprint had they stayed away (likely). Nonetheless, he immediately rode defensively and shut down all attacks after the Poggio descent for Philipsen. Philipsen won the race.
A Monument like that isn't the type of race you give up typically give up to repay a favour. He did it nonetheless.
Also, has Philipsen ever actually been a meaningful help to MvdP? Even in Roubaix, the chasers never stopped chasing just because Philipsen was there, or did they? I can't recall any case. In his Monument or classics solo wins, he just solo'd away without anyone being able to catch up despite trying. Philipsen wasn't the one causing group 2 dynamics as far as I can remember.
