Filaments are fun ways to generate content! They also get gamed a bit for logistics use as well.
So, suggestion: Have a random chance (can be low, like 0.5% or so) that when you activate a filament your ship/fleet gets yeeted into a black hole and destroyed. This shouldn’t impact roams (outside of the rare abrupt/hilarious end) but would curtail people using filaments as escape buttons or logistics bypasses–it adds risk to use them when carrying precious cargo.
So if filaments are intended for combat/content, this sharpens their focus on that activity while not removing it for other uses, although it’ll be a bit more risky.
Or, instead of being destroyed, let there be a slight chance that they get sent to the Eve Gate in Genesis, all within some fun distance from the gate IN that system. That place is a weird anomaly anyway. THIS could generate some interesting content. How many fleets are filamenting at any given time X the chance of going to that one location. Pew, Pew. The ultimate gate camp/drag bubble.
Why not teleport them to the Jita 4-4 undock (or 50 km from the station in a random direction) and apply a one hour long suspect flag and weapons timer on them?