We all have to remember the Tir Accord was written and signed back in July 29470, marking the end of the third Rubi-Kan Civil War, and amended for the last time August 11th 29470, and a few names have changed since – as have certain circumstances.
For natural reasons – like talks between the Council and Omni-Tek shutting down – there have been no further amendments to the accord, and I don’t see that happening until talks resume.
All areas not conceded to the CoT in the document are considered by the ICC as OT-controlled areas.
Neutral guards in Newland City – or anywhere else for that matter, with the exception of the ICC regional headquarters in Andromeda - are not ICC employees or officials, but neutral warriors lending their time and experience to providing neutral citizens with a little security. They are not however, protected by any accords or resolutions by neither OT nor the CoT, and are – as you say – fair game.
The Council are the only ones who have conceded Newland City to be neutral territory. Omni-Tek has made no such concession, and considers Newland City a part of the clan-held territories – as per the accord.
OT considers everyone on the planet not on their payroll – including neutrals - affiliated with the CoT, and will hold the Council accountable for all actions committed by any such individual. OT openly blames the Council for the terrors of the Dust Brigade. That was one of the reasons talks were ended – because of the Council’s inability to deal with the Brigade. In fact, the Brigade jeopardises the accord every time they show their face on the planet. They are wanted criminals, and OT will spare no expense in capturing – and incarcerating them.
The Council knew this when they signed the accord, but trusted their ability to unite the clans under their umbrella. Things changed when Rubi-Ka was opened up to independent colonists and people from other corporations. The Council lost their hold on the non-OT part of the population, and things are only getting worse and worse
The many ambiguous points in the accord have been contested many times during the period, and OT and the Council have had tendencies to interpret them in very subjective light. Just remember what happened up in Sabulum…