.doe> The Tribes of Gad and Reuben both fought in the battles to conquer the land and even stayed an extra 7 years,
Exactly, whether their original statement was clumsy and they planned to go fight or whether they accepted tochacha from Moshe, they joined the rest of AM Israel, while keeping their pastures. So, it is not late for those sitting out now to join tzahal and then return to their studies.
Those who start immediately arguing about different matzav are right of course, but you need first to accept Moshe’s argument of responsibility for your brothers whatever other issues are out there.