Is it acceptable for a married man to sleep beside his mother, cuddle her, or kiss her face, especially when his mother expects him to spend nights in her room and involves him in activities like back massages and Hajama appointments?
Bismihi ta'āla
Men and women, mahram or non-mahram, must always observe boundaries between each other. With mahram, the boundaries are less, but there still are boundaries.
Most of what you have mentioned in your question is crossing the boundary, or should be avoided, so as to not all into haram.
We cannot say he might have incestuous tendency, but it is not normal behaviour for a son to sleep right beside his mother and spend nights in her room, etc. He might have more feminine tendency, hence these activities, but it is also his mother to be responsible for this as well.
I would advise someone have a talk with both of them, about boundaries, and the possible shaytani influence that could corrupt anyone.
And Allah knows best