As per title: are tactic zones considered abilities?
Follow-up question: can Barristan Selmy NCU's influence block/counter a tactic zone effect targeting the unit he is influencing?
How about "Assault Orders"? Can he block/counter it?
Nothing in the rulebook points to them being as such. Abilities are defined as things that appear on Units, Attachments, and NCUs, and are called out specifically each time.