Your boss needs to ask him what the problem is. cookies, alcohol, girl friend, etc. Or maybe he just doesn't take very good care of himself and gets sick easily. Either way, every company/business needs a sick day policy that spells out what is condidered acceptable and what is excessive. Just make sure you don't injure yourself on the days you are working alone by trying to move something (the sander) that is too heavy for you. BTW, I work alone every day and move all the tools myself and I'm 56 years young
I take my time and am careful to lift properly. I dismantle my Hummel sander for transporatation. By breaking it down, it is easily carried around by one person. My least favorite part of the day is moving tools.