I think that you may be on to something. That the tourist managed to get the calf into the SUV without having the SUV being subsequently rammed repeatedly does seem to indicate pre-existing rejection. I wouldn’t want to get between a buffalo cow and her calf.
Me, either. And certainly not without roller skates.
Nursing bovine adults often leave newborn calves by themselves, curled in a ball, for hours at a time. Very normal as the calve risks injury early on if it tries to stay with other adult animals in the herd.
Not a sign of rejection at all. A rejected calf is obviously sick or deformed, even to the relatively untrained eye.
Leave wild, baby animals alone, they need no help.