No, it wasn't a shared victory, it was a "we'll have a big war between us at the end" alliance.
At least, as it was presented way back when.
And from my perspective:
Diplomacy with GS was far worse than with RP. It was practically like pulling teeth. At least at the beginning. I think Theseus and MZ worked well together. After I believe GS relaxed some of their wierd philosophies of waiting 2 weeks to decide anything.