I had my doubts for some time as to wether that was Quote or not as well, but at the end of chapter five when Excerpt says "So long, Quote." it's unmistakably the main protagonist we all know and love from Cave Story. The change of wardrobe and disturbingly large amount of stupidity he shows at the beginning could raise suspicion, but the memories in his memory bank do seem to show Quote with a similar personality to that shown in the mod's present tense cutscenes. But I must say that his character highly deviates from the wise, cunning, well-composed, kind, and gentle Quote I always thought him to be from Cave Story, (almost like a good guy version of excerpt) but I guess that GIR has interpereted him differently. Then again, those memories could have been tampered with, seeing as how what Curly does in those memories doesn't seem to characteristic of her.