I beg to differ.
Traditional RTS games do not most of the time involve an "exploration" phase. At best you'll do some scouting to determine the enemy's build order and/or race, but that's all there is to it.
"Expanding" in Starcraft involves building a few buildings after a predetermined amount of time has elapsed, which isn't really what "expanding" is about (ie conquering or otherwise taking over dozens of "nodes", be they cities, planets, etc.).
"Exploit" is similar, but happens immediately and throughout the game for traditional RTS games, whereas it's a clear phase in 4X games (the order of the terms does matter!).
"Exterminate" is the same for everything so I'll give you that.
I know we're just arguing semantics but I don't think it's wrong to lump Sins as a 4X game even if it might not fit the extremely narrow definition some people have of the genre.