I don't think this will give the defender a huge advantage to get more troops in his city.
situation:
cs 15h away from target, clearing attacks 3 hours away.
conquest: you launch colony ship, defender knows a colony ship is incoming and has 15 hours to time def. after the cs has arrived the defender has another 24/26 hours to attack to cs.
revolt: you launch colony ship + clearing attack, defender knows a cs is incoming and has 15 hours to get def, after 3h clearing attack hits (with revolt) so there is an upcoming revolt, after another 12 hours the revolt starts and the cs hits. So the defender had 15 hours to get def. which is the same as in conquest and the attacker doesn't have to defend the city for another 24h.
Let me make that clearer:
Current: Send C-Ship and clearing waves, for sake of example, the target is ten hours by C-Ship. If defender is online, they can get reinforcements for 10 hours. Then, there are 24 hours where the victim can call upon his/her alliance and friends to attack the C-Ship and attempt to break the conquer
Total time to prevent conquer: 34 hours (24+10)
New: send clearing waves and revolt attack, should take ~2 hours, then there is the 12 hour revolt period for the defender to build up troops, and then the conquerer can send the C-Chip to arrive right after the 12 hours is up, in cases where the C-Ship will have to travel more then 24 hours, the defender has warning even before the revolt starts, but in the example, the C-Ship only takes 10 hours, so:
total time for defender: 14-26 hrs at max and min in the current situation, and the victim has the following advantages: wall and tower (unless they have been catted), militia, divine powers, though these will not be terribly effective.
So to me it sounds like the attacker is having it easier because they can cat down the wall, 375 militia should not hurt them, correct application of divine powers could hurt the attacker, but that requires a good defender who probably was a good player and hopes that they had not already used all their favor.