I know of NO Short Term Health Insurance program that covers injuries due to organized sports. Though rugby might not look organized, it still falls under that exclusion.
IMHO, STM isn't worth the paper it's written on, but hey, if you have a fear of surviving a bus running you over while you're waiting for your benefits to kick, by all means...
Rates are similar: $100-200/month, longest policy is usually 11 months. Some potential to renew.
Remember, if a Prop Falls On You, no coverage. Bus runs you over, coverage.