Fair/Foul Two Man Crew Situation (From a Dad)

[More Cowbell]

You guys are my bible for all things "official." I'm a proud dad who apprecitates the men in blue, and I want to make sure I know what I'm talking about when something comes up. Here's the scenario tonight; I would appreciate any feedback and please forgive any butchered terminology:

My son's Junior Division Little League team (FED rules I think) playing horribly but hanging in 3-0 to first place team with a two man crew. Lead off batter hits shot down the line, PU signals audibly "foul" while the BU is pointing fair. Ball was untouched as it went down the line and past first base. All players kept playing the ball as fair. BR ends up on third. Umpires confer and BR is sent back home and "foul ball" stands.

From what I've read, the PU has the call until the ball passes first base, then the BU has the call. I didn't hear the explantion the umpire gave the coach, but does his "foul" call kill the play even if it wasn't his call to make? The defense did not react to the foul call, nor did the runner. Our team is out of the playoff hunt, but is this something our manager could/should have protested?

To be fair, I must admit that I didn't agree with several call the umpires made all game, but I know those were judgement calls and that's how games go sometimes.

Many Thanks in advance!