CRJ-900 Captain reported that Maintenance deferred a forward cargo squib 2 caution indication. During cruise; they got a master caution for the forward cargo squib 2.

Narrative

Fwd cargo sqb 2 caution msg on and off repeatedly. I called Maintenance and put it in the log book. They turned off the aircraft and on it did not fix the problem. They pulled circuit breakers it did not fix the problem. Then they did a MEL for the problem and the indications went away. I was handed the log book and said your good to go. After waiting probably about 2 hours for weather we departed for ZZZ1. In route we checked the weather again and it had fallen below the ILS minimums. I was texting with Dispatch when we got a master caution. Fwd cargo sqb 2. We ran the QRH and it said to land at nearest suitable airport. We opted to return to ZZZ since we could not even attempt the approach at ZZZ1. after we got to the gate Maintenance was waiting for us. He said that the MEL doesn't prevent the constant on off master cation. I was not told this before and it does not say anything in the MEL. I was then transferred to Maintenance Control. They told me on the phone to disable the cautions on the First Officer (FO) side panel. I believe the FOM says we are not allowed to do this.Cause: no warning of EICAS msg in MEL.Suggestions: Better description of indications in the MEL. Maintenance Control should have knowledge of the FOM.