The whole "honourable noble" thing where almost every character is a knight in a shiny armor who always put his honour in front of everything is much more a modern era idealization rather than an actual medieval representation.
In bm people tend to forget that for the most part, knights was just a little more than bandits with horses and steel.
The Aurvandil's "Noblesse Oblige" doesn't seem less historical accurate than the usual way noble characters are played in bm so unless you want to fully reform the way the game is played I don't think it could be considered a SMA violation
