EMB-145 Captain reported they executed a rejected takeoff after receiving an E(2) REV DISAGREE message. Post flight inspection revealed the inhibit bolt on the exterior of the reverser was missing.

Narrative

During departure from ZZZ we rejected T/O due to E(2) REV DISAGREE which required RTG (Return to Gate) and for contract maintenance to be dispatched. Following maintenance action sign off; the First Officer did a walk around and noticed the inhibit bolt was not in its place to secure the reverser. I called the contract maintenance engineer back to the aircraft spoke with him regarding the completion of the maintenance action. The individual said the external bolt wasn't required and he had secured the TR (Thrust Reverser) internally. I called maintenance control and confirmed that it needed to be there. After extensive discussion and back and forth with maintenance control he appeared to be confused as to direction on finishing the final installation of TR inhibit bolt and floundered to begin the work; he insisted maintenance needed to send through the aircraft MAINT manual for him to see how the bolt was installed and bragged that in 8 years of working on the aircraft he had never had to do this; at this point I noticed the individual may have had an odor of alcohol on his person; I discretely asked operations to verify my suspicion. Once they took some time to talk with him they also agreed there was a smell of alcohol coming from his breathe; at this time the observation was brought to the attention of Chief pilot for appropriate actions as we felt as a crew it was not fitting for him to be working on the aircraft. Around this time he expressed he could not install the bolt as he had stripped it. Maintenance control issued the directive for him to cease work. The maintenance was left as an open write up and maintenance department was dispatched to complete the work. We were re-crewed to operate a different aircraft to ZZZ1.