It is quite possible the in-game GM has not dealt with this before.
Or has not had instruction from the developers or high ups in the company.

Given that boxing has been popular in EQ / EQ2 in the past.
And that there are GM responses saying its fine to do.
The responses these GM's gave seems quite wrong, unless company policy has recently changed.

While any given boxer, is a drop in the sea, as far as revenue goes.
There are quite a few boxers out there, in various games.
A company policy to preclude them from your game doesn't seem a wise option.

I'm playing Warcraft myself.
If Blizzard changed the policy, so boxing was not ok at all.
I doubt I would continue to one-box warcraft.
As I got into boxing, when the game was already becoming stale as a one-box option.

Anyway, see what the GM's say, given they have previous GM approval in the question.