1st off are you really gonna use 9,10 even 11 year old fights to make an argument? Rory probably hadn't hit puberty the first time BJ fought Uno. 2nd BJ is the same size as the three you mentioned and was actually probably lighter than Pulver at the time of the first fight since BJ was walking around at about 145 pounds at that time and could have easily fought at BW if the division had existed.
BJ doesn't want an excuse he has said he hate cutting weight and feels better at WW and the guy wants a challenge. I said it before the effect of his opponents strength on his cardio has been an issue but the actual strength itself has not really presented any kind of problem for him.
I didn't realize BJ fought Edgar 10 years ago, I thought that was fairly recent. Huh. In any case, I was responding to the question "Why doesn't BJ fight stay at LW?" which is always followed by the statement or implication that he would be an unbeatable monster at LW. Since Penn has a number of losses to guys at least his size and possibly smaller I think it is clear that isn't true. He would still be very good obviously, just not THAT good.