Perfectly logical, if terrifying for who's on the receiving end.
Unfortunately, the choice became binary long before Eren came into the picture.
That reminds me of World Devil, the protagonist whereof ends up destroying another world to save hers.
Other people who tried to help the Eldians would just become slaves forever if Eldia recovered prominence. And the cycle would never end.
(Of course, somebody will stop Eren… or maybe not. But the message is a beautifully Hegelian one: when the oppressor and the oppressed interact, positive change must come from the oppressor, who's the only one in a position to show mercy. If the oppressed gains the upper hand, it's unrealistic to expect mercy from them.)