Nothing to do with who attacks and retaliates, it's just a different offence. The rules say a high tackle can just be a penalty (depending on severity), and that discriminatory language is always a red card. Fev received the penalty for the high tackle, but had a man sent off for the discriminatory language.
Hull same again. The game says a knee to the head is an automatic red, whereas a facial can be anything between a penalty and a red card depending on severity.
The alternative would be 'Any time someone high tackles me I have free reign to do or say what I want in retribution', which would lead to some pretty bad things happening.