"At least strongly flirted", precisely, and this is where you are objectively wrong: before this update, even if Lena had fantasized about Jeremy, and even if Lena had strongly flirted with Mike, they were still not an option. Lena needed to have slept with Mike and at least sucked Jeremy AND kept flirting with him afterwards for them to be candidates. So no, sorry, it did not make any sense.
I have a feeling Jeremy might be the one exception. The variable used for most characters is Lena_'character'_dating, and this is usually set to true after a hookup of some sort. It is a little inconsistent, Seymour sets to true if you agree to work with him, even if you quit before anything sexual happens, Axel sets to true without sex, just enough interaction. Jeremy won't get this set to true unless Lena wakes him and blows or fucks him. Ivy's bday party bj is a sore spot for Ian later, and depending on choices as Ian, Jeremy will refuse, be coerced by Lena or be fine with it, but the dating variable is still false. If Lena has the BBC fetish from watching Jeremy/Louise, fantasizing about it a number of times, fantasing about Jeremy enough, he will be a choice for the 3some without Dating True, but NOT on ALL paths.
I haven't verified this to be 100% true, just what I can dig out of my memory, which isn't always right.