Take the trouble to look at the video linked if you haven't already done so. I suggested his view could be partially obscured.
Surely, if a referee does not have a clear view of an incident and then sees the aftermath he would, in the course of being told of the offside call, ask whether the challenge had been checked for a possible red card? Of course without the conversation being broadcast we have no idea whether that happened or not.
I'm not fully conversant with all the VAR protocols but it does say:
The referee must always make a decision, i.e. the referee is not permitted to
give ‘no decision’ and then use the VAR to make the decision; a decision to
allow play to continue after an alleged offence can be reviewed.
I suspect Riley and his merry men would manipulate this to say Oliver wasn't allowed to ask to see something he didn't see properly, or something like that. They've already tried to tie everyone in knots attempting to justify Pickford going unpunished so I'm surprised they haven't chucked this in for good measure.