I'm not saying the head contact was deliberate, and I think any notion of a "witch hunt" is exaggerated- the complaints aren't with the player but with how the officials handled the incident. And you're right, it's not as bad as an intentional headbutt, but just because there are more serious offences to commit, it doesn't mean it's not a red card.
However, Mauvaka definitely "launched" himself at White- and because there was also head contact, that deliberate action makes it foul play. If there was no head contact, it's just a talking to, and at most a penalty. You're right, these types of incidents do happen, and captains are usually given a warning, which is generally sufficient for those situations.
What differs this incident from other acts of players "launching" themselves at others is the fact there was head contact. That escalates the punishment. There's no real argument to make over whether Mauvaka meant to make head contact as it's fundamentally irrelevant to the situation- he did make head contact, he deliberately put himself into that position- it's a red card.