Minos' haste was justified. As much as he could risk it and wait for his advancement to level 90, it could be pretty dangerous.
Advancing to level 90 wouldn't give Minos supreme powers. It would make him much stronger. He knew that better than anyone. But level 99 Demigods would still be a problem for him to deal with.
If the war ended before he made this breakthrough, or even a little later, he might end up in a situation where he would have more enemies than allies.
Even with the support of the dragons, he wouldn't be able to protect himself from anything that might endanger him.
Would those dragons come to the Central Continent to protect or help him? Hardly. They had their own problems!
A war far worse than the one between Vico and Maximillian, a tribe to lead, and a catastrophe on the horizon.
It would be good for Minos and his allies to have more allies at the high level of the 10th stage as soon as possible!