Thats because you dont see the underlaying fundamental changes such declaration as terrorist organization is doing.
The most prominent ones beeing:
In frisco no NRA happening can take place. Guns showing, parties, associations, summits etc
No company/citizen living in frisco is allowed to monetary support the NRA organization- which means they can not do lobby work in frisco, which means money from frisco not coming in anymore to the political active NRA, which means their budget for lobbying shrinks, which means their political power is shrinking.
Which also means nobody paying tax in frisco, be it a company or person, can tax-deduct any voluneer work or money given to the NRA anymore.
This wont happen over night, but with time it has an effect, and if other cities follow then the NRA will dissapear, which will lead to loss of political influence of the “gun-lobby” over senators, gourvernours and presidents -over time.
See the change now?