I actually think his transbigotry was exacerbated by Grimes dating Chelsea Manning to get back at him right after their breakup. Grimes also took a picture reading The Communist Manifesto at this time. This was a huge public embarrassment for him.
I’m going to add I think Grimes was being purely performative here to make Musk angry. Poor Chelsea Manning, a better human than either Musk or Grimes by a million billion percent, she’s a woman with integrity and bravery. No wonder Grimes picked her to upset Elon - Manning is something real and talented and authentic, everything Musk isnt.
I don’t think Elon Musk cares much about his children to be honest, which is why he treats them so so badly.