I would put a towel around the canister then. Your tank wont leak out, at worst you might get a pint or two over a week on a bad leak. I would rather have a leak from a worn out gasket get soaked up with a towel then break the siphon on the filter. If you aren't around and the siphon breaks there is nothing to turn the motor off. You will end up shredding your impeller and burning out the motor once the water is pumped out of the canister back into your tank. You will end up destroying your filter, the bacteria in your filter, and possibly your fish. All this to keep a few oz of water off the floor.
Don't worry about it. With regular maitenence and changing the gaskets and o-rings when they start to wear out you will not have a problem.