Why wasn't the treaty of Olympus hardened with the heresy ?

This may be a stupid question, but why wasn't the Mars Treaty toughened after the Heresy? They had proof that allowing a private army into the Mechanicum was dangerous and had the opportunity to do what the Emperor could not do: completely absorb the Mechanicum into the Imperium and crush their beliefs. Leaving the admech independent could be a disadvantage today: they keep the best equipment for themselves and use their armies for their own benefit without thinking of the rest of the Imperium and the tension between believers of the God Emperor and the Machine God is palpable. Yes they protect the forge worlds but that's a job that could be entrusted to another non-private army, right? By hardening this treaty, they could have transformed the admech in a fully and only production section of the Imperium, not having to negotiate with them every time.

This may be a stupid question, but why wasn't the Mars Treaty toughened after the Heresy? They had proof that allowing a private army into the Mechanicum was dangerous and had the opportunity to do what the Emperor could not do: completely absorb the Mechanicum into the Imperium and crush their beliefs. Leaving the admech independent could be a disadvantage today: they keep the best equipment for themselves and use their armies for their own benefit without thinking of the rest of the Imperium and the tension between believers of the God Emperor and the Machine God is palpable. Yes they protect the forge worlds but that's a job that could be entrusted to another non-private army, right? By hardening this treaty, they could have transformed the admech in a fully and only production section of the Imperium, not having to negotiate with them every time.