Whether or not you can build ToE has nothing to do with your strategy. In fact, a militaristic strategy is more likely to get it, if anything, since it:
a) Eliminates competition
b) Ensures technological parity
c) Ensures productive dominance
If you're playing peacefully, you have to get SciM first or close to it. If you're playing militaristically, you can send troops to capture/raze the AI cities that are building it. You can also use the endless resources of your empire to BUY SciM. You might even have a leader (in vanilla) to rush ToE.