That statement makes no sense to me. It's much more interesting from a narrative point of view if a rogue jedi has the same regalia as the jedi that are out to hunt him down and kill him. To me, at least. They're supposed to be on the same team, and yet there they are: in lethal battle. If you rotoscope his saber yellow, you've already - heavy-handedly, I might add - said he's not on anyone's team - and the mystery of his character is deflated faster than you can say "Geonosis".

Also, such symbolism presupposes an off-screen event where he gets his yellow saber once he leaves the jedi order. At some point he must have said to himself: Now that I'm no longer with the Order, I need a different saber colour.

That's not my idea of a good plot point. And it's IMO way worse than the actual prequel story where he probably got his red saber from Palps (a plot point that makes sense and serves a purpose).