So I'm assuming everybody starts at -100 hostility, then according to whatever hostility settings you have set towards a side (low = 0, medium = 30, high = 60) will be added to the initial -100 starting point to give your average hostility. This would explain why a lot of the hostilities for the OPFOR are at -70, because they're set to "MEDIUM" hostility.
This kind of brings a problem up with the updateSectorHostility function, because the function will go based off of the hostility setting you have, so if you add 50 hostility to a sector that reads -70 in the OPCOM debug, it will turn into a hostility of 80 (the medium setting of 30 + the 50 hostility you added) or sometimes 90.
It seems like the hostility will drop down to the proper updated hostility after the player leaves the area (was at 90, I left, dropped down to -20).
I believe while the player is in the area, it automatically sets the hostility to the hostility setting of the OPFOR, so in my case medium (30) plus 10 for player presence. Giving a default value of 40 when I enter Timurkalay.