While playing the TEC, I was assaulting a system with an advent (stationary) starbase. I cranked out a bunch of scout frigates with the timed explosives ability, intending to swarm them onto the starbase to set their explosives and hopefully put a big dent in the starbase.

Imagine my surprise when I am told that I can't use this ability on the target unit (the starbase).

Timed explosives are for use against orbital structures (as distinct from ships or planets).  Is the stationary starbase not an orbital structure?  Sure as heck oughta be.  If it can't shoot down all of my frigates, they should be able to plant their explosives.

apologies if this came up before; I searched the forums and got no hits on this.