In order to retaliate, you also need to know the enemy‘s waiting room coordinates, but since Watevr doesn’t have the coordinates neither the other masters whom been fooled before, non of them could even take revenge.
That does make sense in a real/fantasy world. Facing an unexpected attack from unknown sources & with everyone on floating island/ship would mean it is next to impossible to locate the attacker base, especially with other resources focus on repairs & fortified against future atk. I can see this happening in game like Civilization (never played, but it strike me as something that could happen).
In Mobile game though, I would expect Dev to give like player stuff like a 2-3 days immunity to further atk after a raid, with an option to retaliate & some discount on speeding up repairs/build troop to provide incentives for players to cash in & create interaction instead of just sitting solo.
Heck, if I was really money hungry, I would expect something like "enemies trail are still fresh, can retaliate within x H before trail goes cold" & maybe "trail gone cold, upgrade ABC to map/set alarm in general area". First option + long troop build time = player more likely to spend vs waiting for units naturally via farming materials. Second option might not get player to spend real currency, but they will stay long term & to farm & upgrade to be prepared for next time.
Of course, deciding to retaliate will cancel shield.