When the remains form surely they contribute to microlensing. But after they out of the visible Galaxy boundary, they stop. And given the end up 2-3 times from

When the remains form surely they contribute to microlensing. But after they out of the visible Galaxy boundary, they stop. And given the end up 2-3 times from the boundary, they spent the vast majority of the time there without contributing to lensing. Now consider that according to the paper 30% is going to leave the Galaxy. Those after the initial travel will never contribute to anything.