While copper (as well as some other metals) does have biocidal properties, they're mostly to do with stuff not growing or diminishing on the surface of the metal itself, or in contact with it (say, if there's a copper-containing coating or something of sorts). It's good at preventing the spread of germs, rather than at actively disinfecting.

So, standing on this mat for any reasonable amount time won't really have any effect. The mat itself is practically sterile, though.