Regulation 261 doesn't apply to Schedule Changes ... yet. But the EC is thinking about it.
See their consultation
here. See Question 5.2
You've got until 1 April to respond. Some of the questions are from cloud coo-coo land (i.e. should they legislate seat pitch?) But if you want your views known, this is a good start.
Most network airlines will give you a full refund if their schedule change isn't acceptable, and they can't rebook you on a flight that is. That could still leave you out of pocket - but it is still better than this tactic.