Origins of the \'Hollywood\' Roman salute?

[Praefectusclassis]

I have no doubt that anyone in a position of legate, governor or other high magistracy would assume the outward posing that goes with that rank.

Class became less about birth, and more about politics, but I don't think they every gave up the notion of "class". The question is did native born patricians distinguish themselves from the noveau riche and upstarts? Would it even have mattered by the latter empire?

No, the notion of patricians and plebeians had become completely irrelevant and this terminology was no longer used. Instead, it became important whether you belonged to a senatorial or equestrian family.