I just read this last night, and from this I had the impression that it is an airborne virus, and that surface spreading is not the main vector:
https://www.cdc.gov/coronavirus/2019-ncov/about/transmission...
Airborne transmission doesn't require any other medium than the air itself, even dust is optional.
No amount of gentle reminder -> passive aggressive suggestion -> explicit suggestion had lasting effects on their behavior. All I could do is be vigilant and recluse myself from their company whenever one's clearly showing symptoms.
I wouldn't use a urinal either (I never do anyway, as a former licensed plumber, thosef'n things are NASTY imo). I also flush twice with my back turned before using a public toilet.. not ideal but better than not I think.
I work in hospital
Flushing toilets leads to aerosolized water droplets from the toilet spreading around the room and contaminating nearby surfaces[1].
So if droplets containing viruses penetrate beneath the surface of the mask, sterilization with light will not be able to reach them.
A saner advice is to wash your hands frequently and to avoid touching your face when in public. Because you can get this virus by touching infected surfaces and then touching your face. It doesn't seem to be an airborn virus, but it does survive on surfaces.
I cary a hand sanitizer for those moments in public when I feel the need to scratch my face :-)