I've heard the same thing about transporting flat screen TV's laid down... maybe it's specifically how they could be damaged and they can tell then when you make a claim? I'm not sure...
But also, you're doing it wrong. Get a BenQ HT2050a 1080p projector and a SRT 110" projector screen all from Amazon for about $1000 total. You'll be blown away compared to any 65 inch TV!