It's actually not that simple. The menu is what sets up which tracks are selected. I've got maybe a handful out of my 800+ discs that default to lossy tracks. In the case of Batman Begins, as pointed out, there's no menu which might be why it's defaulted to a lossy track. In the case of DTS-HD MA, where DTS is a core track and the MA is an extension, there's no need to default to anything else because those that can't play the MA extension will default to core. TrueHD is where it gets trickier, which is what Batman Begins is. There's no core lossy audio in TrueHD...AC3 is a separate track. And those are the ones that could be defaulted. To jmone's point, I never tried to bring up the popup menu to switch the audio track as I didn't think of it at the time. I instead opted to switch to title playback which LAV then detects the TrueHD track and selects it on its own. You'd think there'd be some kind of "standard" but blu-ray is quite frankly a mess.
In any case, the reason for posting it here was in case there was an issue with the menu code. There is not. It handles the disc exactly the same as a licensed player which is exactly what I would expect it to do.