When they started this you could see everyone’s GAC history by putting in any ally code. Now it seems that you can only look at people that have a gg account. Probably something to do with privacy laws in some countries.
If that’s the way it’s going to stay then I would prefer they make GAC history private, but they won’t. At this point if GAC is your priority in the game, then it probably makes sense to simply delete your swgoh.gg account so you don’t give your opponents an obvious advantage.