CBMod Seekers

[Captain Kwok]

Anti-seeker weapons are auto-fire only. This means they will only work for auto-resolved tactical combat or simultaneous combat modes.

[Suicide Junkie]

The short answer is that the SE tactical combat User Interface does not allow you to fire on seekers.

so, Strategic combat only.

Tactical is like cheating against AIs anyways, and you can't do tactical in multiplayer games.
Besides which, you don't *want* to do tactical combat with 300 ships and 5000 fighters blasting each other