Comment: You offer the most reasonable approach for this group.  However, that isn't what they are going for, IMO.

To your first paragraph, I point to Rules for Radicals, Nos. 4 and 13.
The letter itself is a classic example of using all of the RfR except, perhaps, Nos. 9 and 12; I doubt that Paprocki (or anyone, for that matter) believe this group is any actual threat nor does there seem to be a fallback if their opposition fails.