Just to rip the scab off the silicone debate again... I've always used neutral cure kitchen & bathroom sealant with my enclosures, with no apparent problems. I think you'll find that the hazards indicated in the MSDS are released during cure. Most silicones (neutral and acid cure) are extremely stable for many years once fully cured. If they continued to outgas over a long period of time, they would very likely noticeably deteriorate as they age.
Don't forget that we place our animals in enclosures made from particleboard which has formaldehyde (less now, but still there) as an adhesive component to hold the matrix together. I wonder how much of this noxious, carcinogenic gas migrates through the thin melamine coating into the enclosed, poorly ventilated space in which our reptiles live. Even if you keep your snakes inside your house, they are exposed to a whole range of airborne chemicals, from kitchen fumes, carpet chemical outgassing, cabinetry and paint chemical outgassing. I would suggest that a minute bead of mould resistant silicone is very unlikely to cause any problems for a reptile inhabitant, considering all the other noxious substances they are exposed to.
Jamie