Yeah some brands of silicone sealants made for aquariums do give off chemical vapors as it cures just like all glues, but I wouldn't be too worried about it. Acetic acid in liquid form are indeed corrosive to some types of metals but in vapor form the concentration is so low and in the short period it takes for silicone sealant to cure it does no harm whatsoever to RC level electronics. However there are some brands of silicone sealants that only give off petroleum based vapors which is exactly the same given off by shoe goo.

With that said, if you had a constant supply of acetic acid vapors surrounding mission critical electronic SENSORS like on the space shuttle then that would be different.

To be honest, I'd be more worried about water vapor in the air over time doing damage to RC electronics than a few hours of acetic acid vapors in a well ventilated area during the curing process.