I’m not sure I understand the salt regarding the latest Doctor Who Christmas special. But maybe it’s because I really liked THoRS and I like River and how her end met her beginning?
Why wouldn’t he be upset? He just spent 24 years with someone before she left to meet her end. Is it because people think he should be mourning Clara instead? Literally, Clara who? His memory of her is gone at this point and whatever residual grief he feels for a person he cannot name/visualize/remember has snowballed into grief for one he can.
I think he’s finishing the evolution of self he had begun last season. 99% of it was due to Clara’s influence and without that, the Doctor of these past two Christmas specials would not have existed. Seeing him now (and likely seeing his initial interaction with Bill till she has her own impact on him) is like seeing Clara alive in him.