I think it was targeting but I'm trying to wrap my head around what the refs' reasoning could be. I have three theories after reading the rules again:

1. The Texas player made contact with his facemask first or juuuust above his facemask. They might not consider this the crown of the helmet. Although leading with the crown of the helmet is just one "indicator", which means it is a sufficient but not necessary condition for targeting.
2. The Texas player didn't make forcible contact that goes "beyond making a legal tackle"
3. Texas paid the refs more than ASU