I noticed if I change the category setting Search Priority to Ignore it will Ignore globally the category and topics inside it on search inputs even if I want to move posts from a topic to another topic which inside a search ignored category.
Set the category Search Priority to Ignore
Create a topic in the search ignored category
Try to move post to the existing topic what you created in the second point. (The search on the move posts modal will not find the search ignored category topic.)
This is block the move posts feature to the those topics.
IMO the workaround by @JammyDodger here is fine. Adding ignored categories to the search results there could overwhelm the operator, they are ignored for a reason.