Just to check up, you're claiming that the most realistic reaction of:
the Hegemony, (who hates TT and the Diktat, and has stressful-at-best ties with the Persean League)
the Luddic Church (who hates TT and, well, technology in general)
the Persean League (who exists solely because they hate the Hegemony more than they hate themselves)
the Tri-Tachyon (who hates the Hegemony
and the Sindrian Diktat (who hates the Hegemony and foreigners in general)
Will all huddle together, set aside their centuries of differences while singing kumbaya, and collectively unite into a five-nation army... because you have a hat trick.
No and yes.
You don't have to sing jumbaya to assisinate the same person. Things is none of them would want their piece of tech to fall into the hands of the other. They would rather see it destroyed. If I can't have it, no one can.
Of course, I'm under no illusion that the second your fleet is blown to bits the assasination armada wouldn't turn on each-other, in an effort to either steal the key or destroy it.
Yeah no. While the prototype Janus device is a useful device, it's not by itself a mechanism whose mere possession would warrant blatant declarations of war (except perhaps from the Sindrian Diktat, given their perspective on the Ziggurat), let alone a military union of nations to form against an otherwise mostly law-abiding citizen of the Persean Sector. That's not realistic, and it's just not how politics works.
You have no clue what nations and secret services have been up to in the real world do you? Truth is often stranger than fiction.
A device that allows an entire fleet to pop into your backyard is a massive security risk. And while you might be a "law-abdiding citizen" (or maybe not, you can me a murder-hobo supreme), that device wont' stay in your possesion forever.
Granted, the entry points being known reduces that danger somewhat.