From: Rabbi Akiva Eiger
To: Unknown recipient
Rabbi Akiva Eiger distinguishes two independent bases for the principle that a davar she'yesh lo matirin is not nullified: the min b'mino framework (applying to items with immediate permissibility, the Rif's chiddush) and the ad she'tochlenu principle (applying to items with only future permissibility). Under this framework, the kilayim case is resolved: since the mixture is yavesh b'yavesh, the min b'mino track cannot prevent nullification, and since the wool was never independently forbidden without linen, the ad she'tochlenu principle also does not apply. Rabbi Akiva Eiger acknowledges that this resolution holds only on his own reading of the Rif, while for the Ran's interpretation the difficulty remains unresolved.
Source: Shu"t Rabbi Akiva Eiger §209