Mu Lab XT Limitation- not Able to mixdown in 32 bit

[ActiveKoala]

Can someone please explain this limitation for me.I'm new to music software and don't know much about producing music in 32 bit or 64 bit;all i know about 32 bit and 64 bit(when its related to music software)is that I can access more of my CpuRam with 64 bit, and that 32 bit renders a smaller file.
-Why do I want to be able to mixdown to 32 bit?

[MuTools]

http://en.wikipedia.org/wiki/Audio_bit_depth