My replies in red. Moo..(guess that makes me UNreasonable in some peoples opinion.. oh well!)
Not unreasonable. Only it opens some questions. For example, how do you reason, that MBB made a phone call from the bus terminal and from there, in your construction, she not only pulled a quick trip (instead of taking the bus home which was her expressed intention) but also by pure chance ran into the guy who would start a series of murders. He was in a place, he couldn't expect a victim at a time, he couldn't expect a victim. So, you can construct any theory about she pulled another trick, but in the end, it is what it is, a construct.
And by the way, if this john who made out with MB, ALC and maybe MW didn't use a burner phone, LE has long found him and excluded, but if he used one, we would as certainly heard about that as we heard about the phone calls to Amanda.
Of course, it has to be a strange john anyway. Three of the victims offered basically very normal sax, one offered femdom. So what would that make this hypothetical homicidal john? A sadist and a masochist at the same time. Someone who likes to be tied up WHILE he ties up his dominatrix? Maybe, since you try to sell this theory, you can explain those discrepancies?
So, as of yet, I'm not convinced about this sadomasobyaccident homicidal john. Maybe you can supply some more arguments for your theory, so many people (and not all just posters) believe in?