Feel like I'm repeating myself here, but they're moving less than half of them, which is going to have a negligible impact on a state with sufficient ASAT weapons' ability to create a massive mess with the many thousands of Starlink satellites operating in their original plane. Not even like the satellites in the lowest orbit are insulated from the effects of debris cascades set off in higher reaches of LEO either

Plenty of operational reasons to want a large fraction of your constellation in a slightly lower orbit, none of them involve "terrorist states"