Probably because even the largest ship in Chinese CG fleet had bulbous bow to save some money up to this point. Now I see big guns (used mainly aboard warships) and lack of of bulbous bow (which says something, at least for me as no one had pointed that out earlier) in those projects. There's no logical reason for doing that. And remember that Chinese CG cutters had a history of clashing with almost every CG of it's naval neighbours. I can't remember reading about US CG in the same manner...
76mm gun is hardly unprecedented for coast guard cutters. USCG's Hamilton class were armed with them.
If you really want to talk about warship grade weapons, you should look at the USCG's Legend class cutters which have Phalanx CIWS for crying out loud, which is a much more navy-exclusive weapon compared to DP cannons and autocannons.
As for supposed lack of bulbous bow -- again, ships with or without bulbous bow can all do intimidation and ramming.
You're really better off arguing that the entire CCG is capable of doing intimidation and ramming than trying to say that ships without bulbous bows are somehow meant for ramming or more meant for ramming than without.