Why does the left has such a problem with republicans voting for Hilliary in TX?

I am confused by how angry the left his that republicans are stating that they will cross over and vote for Hilliary in the primary in TX. Texas is not a closed primary, so each voter is allowed to vote for whomever they choose. I didn't see any of them complaining when the democrats were all crossing over to vote for John McCain??? Where was the outrage and charges of sabotage for this? Such a bias, if I lived in TX I would vote for Hillary also.....just to spite.