Galahad is probably the most chivalrous of knights. He's ever so polite when the Frenchman is taunting him and his companions. Arthur asks them what they're doing in England if they're French, to which the Frenchman yells, "mind your own business!"
This exchange makes Galahad looks away timidly, as if he'd just committed some offense by overstepping his bounds in this new relationship with the Frenchman. After the Frenchman has finished insulting them quite thoroughly, Galahad's only response is, "What a strange person." It's as if he's not even offended or assumes the Frenchman's intentions to be good. He even nicely asks, "Is there someone else we could talk to?"
He even respectfully corrects the mathematically challenged Arthur:
ARTHUR: Right. One, two, five!
GALAHAD: Three, sir.
Galahad may be a bit naïve, but he's certainly a knight's knight when it comes to being gallant.
But there are some things that Galahad is wise enough to fear, namely the perils of evil temptresses. Notice how he says his name is Galahad the Chaste, emphasizing the sexual meaning of his true title of Galahad the Pure… in case we didn't get it.
Is Galahad naively squandering the chance of a lifetime, or does he barely escape eternal enslavement with the hotties at Castle Anthrax? We never find out because the brave Lancelot comes to his "rescue." But we have a feeling that, based on Zoot's reaction and the nature of parody, that Galahad missed out on quite the opportunity. Chaste or not, he seems to think so:
LANCELOT: We were in the nick of time. You were in great peril.
GALAHAD: I don't think I was.
LANCELOT: Yes, you were. You were in terrible peril.
GALAHAD: Look, let me go back in there and face the peril.
LANCELOT: No, it's too perilous.
GALAHAD: Look it's my duty as a knight to sample as much peril as I can.
LANCELOT: No, we've got to find the Holy Grail. Come on.
GALAHAD: Oh, let me have just a little bit of peril?
Galahad leaves the castle without getting any "peril." Poor dude.
Do Nice Guys Finish Last?
In the end, Galahad's sincerity is what does him in. He's such a nice guy that, every time Arthur says "five" when he means "three" (which is sometimes a very important distinction, like when you're performing hand grenade rituals), Galahad politely corrects him as if it were the first time he made the error: "Three, sir".
When it's his turn to face the Bridgekeeper, Galahad is as sincere as ever. He says his favorite color is blue but then quickly realizes that it's not. Good Guy Galahad can't even spin his mistake as the truth. When his honesty gets the best of him he's sent flying into the gorge. Sometimes nice guys do finish last.