In age 1 that is true, in age 2 not so much. The main question here is the role of the suzerain. Does he reinforce the colony or risk losing it? If so, do the troops in his main automatically fight or do they need to be sent to the colony? Realistically you would expect that his role would be to manually send troops, but no one (so far) seems to be able to say with certaintly yes or no.