I don't know the Jr. Legion rule set, but I suspect that it includes not only FPSR but some kind of "slide or avoid contact" rule. From your description, I can't tell whether the runner complied with that rule. You say both that the runner braced for a collision, which suggests that he intended one, and that the catcher was pulled into the runner's path by the ball, which suggests that he was avoiding contact.
You have to decide which of these is correct. The former is INT, MC, runner out and ejected. The latter is a train wreck in OBR (possibly OBS in FED, depending on when and where F2 had the ball).
It sounds as if you tried to split the difference on the field, which doesn't really work.
