Sealing them is unnecessary.

Asbestos is a fiber, in floor tile it is already encapsulated in the vinyl used to make the tile. The only way you could get these fibers airbourne and create a health risk is to sand or grind up your tiles. Don't sand or grind up your tiles!!

Sealing of asbestos is really only necessary when it it is in it's fiber state (insulation).

Cover them and forget about them. There is no risk to your health or your family's health.