A RUBBER mallot has some definite uses on a bike - one of them being inserting SOME bar plugs in hybrid or mtb bars. But I have SprinTech mirrors myself and can insert them ny hand. Its possible the bartape wasn't installed to 'best practices' and there was too much tape stuffed inside the end of the bars. Using a mallot isn't an ideal solution, but possibly the alternative would be retaping the bars. If the rubber mirror mounts weren't damaged there's no reason to suspect damage to anything else.