Patrick,
The MEK itself is not a sealant. It keeps the sealant viscous until it's applied and dried. Seal All could be filled with other solvents and have the same results. Once it's applied and dried, the MEK will have evaporated.
Like you said, be careful where you touch it. It will eat the oils off your skin very fast. Acetone is harmless compared to MEK.
Not that you didn't know that but your post sounded like, "Hey this is good stuff, it's MEK".
