I'm a little late to the party, but I think it might be more of an artistic choice than anything else.
Victor's arm is probably there to protect their own private moment together instead of it being due to censorship reasons.
There's a post on tumblr here that cites Kubo-sensei's tweet as an 'official' confirmation of the kiss. I'm a complete novice at Japanese, so the reliability of this source completely hinges on the OP's translation. If the source is right, however, and Kubo-sensei's tweet indeed heavily implies that the kiss is in fact, canon, then I don't think censorship is really much of an issue here.
Some have cited the cultural norm being the main reason like you mentioned, but I think it doesn't really hold if you examine what happened in the later episodes. They proposed and literally got engaged with gold bands on their fingers, and if the entire series was meant to be reflective of the queer culture in Japan, I kind of doubt that would happen.
What I have said is just mere speculation though; please take it with a pinch of salt.