Do you really want to have time traveling Gods fucking around in your timeline? This technology isn't a nuke, nukes destroy stuff but don't put the entire universe at the constant risk of collapse.
Imagine Banagher telling the Anahiem techs that they had discovered time travel but in doing so his soul had been absorbed by the Gundam. He ceased to exist and the machine (which as you recall was designed to genocide newtypes) was now in control of him.
Do you really want a genocidal time traveling Gundam that can block any attempt to attack it and disable every weapon that comes near it? It would be utterly unstoppable and if not for Banagher being such a beta then that would have been the menace running around UC.
This would be an awesome cross over side story.