I have no intentions to sell or buy anyone else.
Just to be clear here, you can sell players while homegrown, why not?
If you get draftee you don't intend to train, sell him. Or if you want to replace your older player with new draftee - sell the older guy. That's not against the rules. You simply should not buy any players, all of your guys should be drafted (or already on your team if you're new team).