SIU was less than specific of course but we generally know that the army "dealt" with this somehow. And it is an unquestionable fact that for the army there was an unassailable red line when it came to the last station hence why they relied on hostages to lure bam out.
Thats just a just so. The army dragged Bam out by some means sure but they werent just dilly-dallying around. If Bam didnt come out i would think they would have other means to get the battle to him. Especially Kallavan at the end or Sharon (when she faced off Bam only to be paired with White), They intended to kill him off. Admin definitely observed it all but showed zilch interest in intervening.
Also SIU can bring up 100 s of such exceptional zones of fight where Bam can be and would be lured to duke it off with high rankers of Zahards forces. As he is exposed Zahards army, i doubt, will be complacent enough to let him climb to 135 and then attack. He will be attacked and so will his friends be attacked.
In the end I doubt with all the mayhem that is to come Bam will get to prioritize climbing rather than being on defense and fighting these forces off one by one. I think that the rule of not attacking regular is a general guideline and it can be circumvented if there is a need especially when the order is coming from Zahard who has the seal of approval from Admins.
And then there is Yuri attacking Karaka almost killing Yihwa and Rak only to be saved by some deus ex machina. Karaka trying to kill Bam off etc. The prohibition seems quite malleable and thus i doubt Zahards army wont utilize it to their advantage before Bam reaches 135 with/without howsoever timeskip you can fit in the story.
Not to mention now that Bam is on ranker level power we need to have powerful rankers and highrankers as Bams opponent to make things difficult for him. He just 1 shotted few C rank without even batting an eye in the Kallavan arc. He has grown substantially now, I doubt a score of A rank will pose much of a threat to him.