Or it’s just a publicity stunt to calm sponsors
I think that's equal to the same tbh.
Visma is going to the Tour with the cards they've been dealt. The management wants Vingegeaard there, the sponsors want Vingegeaard there & I'd hazard a guess Vingegaard wants to be there.
The part I strongly disagree with is the assumption Vingegaard must have fine form & TdF winning legs to be on the startlist. I don't think so. In fact this sport has often demonstrated the complete opposite: riders go into races with subpar condition for a myriad of reasons, namely when that's all the team has.
What was the alternative? Kooij in sprints for stage wins? That's just kicking the can down the road because they've got the same problem: a stronger rival (in the case of sprints, Jasper Philipsen). So I think they'd rather take their chances with a shot at a decent GC with Vingegaard.
Like I said, a podium can be achieved with a 10 minute deficit on Pog. I assume that must be part of their thinking as well.