How old was WvA at that race? One should not expect mature behavior from a 15 year old fully pumped up by adrenaline. Hopefully, after the race his coach told him to get a grip and behave should he want to continue on the path as a professional athlete.
The WvA of today knows how to behave properly. Watch the post Paris-Roubaix interview. No excuses there.
Is it proper behaviour to extend your middle finger at a rival after a sprint?