Planting a satchel charge near a Cop gives you 4 star threat suspect.

Not 100% sure but I think this is a SA-MP issue as the satchels aren't very synced.

Maybe it could be implemented where

if $satchel_ammo -1
then crime committed: planting explosives

edit: but also could make false su with how SAMP and ammo amount sometimes drops by itself etc

Yes we couldn't really detect where the satchels were thrown out.
But we had their ammo, so it is implemented in the next update and the thrower is marked as a threat.