I was typing on my laptop for that email and misspelled RSI. Sorry for that.
And you are correct, they never mention shorting when a stock or etf is above the 200 day. However, I do it all the time and the rules still work very well. You just have to do the scale in approach rather than the normal 1/2 size entry and double down like normal.
They call it the '1,2,3,4' entry.
10%, then 20%, then 30%, then final 40% of total position entry as it keeps moving away from you.