Apparently you're ignoring the part where the colonists were intended to be relocated and -at their request- were given the -option- of staying where they were under Cardassian rule.
The Federation was protecting its people by signing the treaty. Specifically they were protecting millions of people from a war with Cardassia. Treaties -always- involve compromise. It's the way the universe works, and yeah, it sucks if you end up on the short end of the stick, but if you'd really rather have a war between two powers than move? That, IMO, doesn't speak well of you.
We have no idea exactly what the Feds may have done once they became aware of what the Cardassians were doing. Sisko's team made a point of trying to stop the Cardassian arms shipments, but "The Maquis" doesn't make it clear what other repercussions may have ensued.
As far as I'm aware the Federation didn't particularly do anything to actively end the Maquis threat until Eddington's group started openly attacking Federation assets...good move on his part....