I don't think Hagrid is anti Muggle, he's only belligerent there because of the Dursleys (that is, their behaviour, not them being Muggles). Let's remember that:
- he just tracked them because they wouldn't let Harry read his letter
- he just learnt that Harry did not knew he was a wizard (or that wizard existed, as a matter of fact) and that he has always been told his parents died in a car crash (and, if I recall, Hagrid almost took this as an insult to their memory - sorry, I don't have the book around)
- Vernon Dursley insulted Dumbledore... and well, Hagrid does not really like this.
So yes, he's quite angry! But just because of this specific situation.
(Also, Hagrid is not really a "let's calm down and quietly talk about this" kind of guy.)
Furthemore, we never see him being violent or anything toward any other Muggle, do we? He goes in the muggle Tube, is friend with Hermione (she's not technicaly a Muggle, but anti-muggle people usually don't become friends with muggle borns)...
PS : In my opinion, quietly reasoning with the Dursleys to let them change their minds would not have worked... but that's another question ;)
EDIT Just found two dialogs where characters themselves explain the "it's not cause the Dursleys are Muggles, only cause they're awful people" feeling :
“Why would I want to attack Muggle-borns?”
“I’ve heard you hate those Muggles you live with,” said Ernie
“It’s not possible to live with the Dursleys and not hate them,”
said Harry. “I’d like to see you try it.”
(Chamber of secrets, Chapter 11, The Duelling Club)
and later, about Dudley:
"We didn't give it to him because he's a Muggle!" said Fred indignantly.
"No, we gave it to him because he's a great bullying git," said George. "Isn't he, Harry?"
"Yeah, he is, Mr. Weasley," said Harry earnestly.
(Goblet of fire, Chapter 5, Weasleys Wizard Wheezes)