A knife shouldn't be required as the Safety belt latch on the Toilet should be perfectly serviceable. It is the End users responsibility to ensure that corrosion of the metal latch is minimised if using non standard TSA compliant belt latches.

The automotive car safety belt type should be universally accepted and serviceable although the aircraft safety belt type which was originally fitted in early TSA standards may take some a little more getting used to.

Of course, care should be taken when using larger lavatory bowls when visiting folks who have them specially installed as the belt tension could make falling into the bowl a small but significant safety issue. Does the TSA accept liability for such distressing incidents?

In Europe we have yet to follow the safety standards set by the TSA, in fact there are no standards for TSA safety. But then again folks in America doesn't have to adhere to the Draconian EU Banana specifications with regards to bend ratio, length and girth size.