Can't really enforce anything else past the first merge
This. Factor in lag and differing views between players (it's completely possible to see your opponent not have a guns solution on your end while they actually have one on their end due to naturally-occurring delay) and you just can't enforce them in an unbiased manner.
Not only that, but a neutral, mid-altitude, guns-cold (what you call "no HO") initial merge where anything goes afterwards is the de facto standard for virtually every air combat sim to date... and for good reason - it's how real fights are flown even today.
Seeing as this has been the format for even the 1v1 bracket tournaments, I'm not sure what the issue is here. The merge, as described, allows for a completely neutral merge - no one holds the advantage or can gain the advantage prior. Afterwards, everything is based on tactics and their inherent merits.
This type of setup shows which tactics actually work in air combat... and which ones don't.