You gain 6xp disarming dynamite at the health and ammo cabinets, the console messages says disarmed at said cabinets.
The game does the same thing at MG nests.
I think the bug is not gaining the 6xp disarming, I think the bug is getting the 6xp for disarming your OWN dynamite.
I can see getting XP for disarming the dynamite of the engineers of the other team because they could plant in these areas to try to kill enemy team members getting heal/ammo and firing MG’s
More about the constructible MG nests, If you are and axis engineer at an axis buildable MG nest and plant disarm at it you get 6xp, if you are an allied engineer you do not. I’d assume if an allied engineer planted at an axis constructible, the axis engineer would get the 6xp disarming. Same with allied engineers doing the same.
The 6xp is because you’re defending your team, the bug is getting the xp for your own dynamite.