I would also suggest putting some polysporin on the sore to try to prevent any infection. The bandage might not be a bad idea, and it's possible the cat doesn't have much feeling in its tail anyway, which means he may not be bothered by having it wrapped. By the way, are you sure it's a male? Calicos are almost exclusively female.
"To close your eyes will not ease another's pain." ~ Chinese Proverb
“We must not refuse to see with our eyes what they must endure with their bodies.” ~ Gretchen Wyler