Air ship for anti air , strike role , why not ?

Why dont they use airship as a super weapon ?
ISIS program plan to make an air ship hover at around 60-70k ft , with skin as AESA radar able to see out to 600-700 km , the energy is provided by solar panel , the airship can hover for several months
my question is why dont they use it as a weapon ?
Equip it with missiles like ESSM , SM-2 , PAC-2/3 , METEOR ..etc
and bomb like gbu-28 , gbu-53 , jsow-er and it will be pretty unstopable
I mean it have many advantages :
1- very long radar range ,not limited by radar horizon
2- very high altitude = longer range for aam and bombs , immune to short – medium range SAM => detect enemy first , hit first
3- very very high load out compared to fighter , bomber , sam , ship ..etc
4 – very very long loiter time => very good for SEAD
5 – almost stationary = invisible to radar ( doppler radar ) , stationary + jet engine = almost invisible in IR , can be painted in color that blend in the sky too
6- even if it was hit , airship go down much slower than fighters