The title pretty much says it all.
I believed that I could use Joshua B. at the beginning of a turn, take another click. Then, at the end of the turn, choose to activate Joshua's end-of-turn first, get a tag, then activate Citadel to remove said tag. A friend says this can't be done. I countered that the stack doesn't exist in Netrunner, and it's not like both abilities go on the stack at the same time.
Do we have a rules expert or official ruling on this?