Spoiling the tolerances of internal components is complete hogwash and poppy-cock. It does cure quickly - you have about 45 minutes to work, but that's about standard working time for most sealants.
I haven't read that in the Automotion catalog, and I've never talked to anyone who has used that. Take it from me (I know), the people creating the catalog don't always know too much about the actual cars...
-Wayne