User blog comment:SlyCooperFan1/ACZ Canon Ace Style?/@comment-4503347-20120819190122/@comment-4503347-20120820105704

It's a valid point that the lack of the AC5 characters in soldier style or knight style would make them seem as if they are non-canonical. The way I see it is that the Belkan War is a fairly large scale war, so it could be that Cipher just simply did not cross path with them on those "scenarios", much like how some of the operations in ACZ are split into smaller missions such as Juggernaut, Merlon, and Final Overture, so that they all happened around the same area, but are not depicted in those particular cases.

Another possible reason as for why Grabacr, Heartbreak One, and Pops would not show up in soldier style or knight style of Mayhem could be that they Pops might have deserted in a different direction other than the Round Table, of which the events of Grabacr shooting down Pops and him meeting Bartlett would still happen, but just not on the Round Table itself (as they never mentioned where they had this occurred).