At E3, MS constantly referred to Splinter Cell: Conviction and L4D2 as 360 exclusives, even though they are coming out for the PC.
Nothing new there. PC has always been kept separate. Sony does the same thing.
I highly, highly doubt neither Microsoft nor Remedy would go bankrupt if they released the PC version at the same time as the 360 version.
It's not simply about not going bankrupt - businesses don't exist to not go bankrupt.
The more I think about it, though, the more sure I am that Remedy was in major trouble.
Where are you finding these sales figure? I found the 7 million total figure and I found that MP1 sold about 4-5 million and MP2 sold about 1-2 million. I haven't found any sales per platform. And again, the Game Boy version wasn't made by Remedy so I doubt they made any profit from it.
Wikipedia. All it has is the PS MP1 sales, at 2.1 million. They've got it sourced so I trust it. I think the Gameboy version came when Remedy still owned the rights so they still made something from it, but that's moot, anyway. I wouldn't expect those sales figures to really impact anything, although it was well reviewed.