The different operating systems are dropped depending if or not Microsoft supports it. A while back Microsoft did a press release stating Win98 would not be supported and LabVIEW was developed accordingly. Some time after the fact Microsoft backpeddled and decided to extend support but by this time it was too late to add this back into LabVIEW. Windows 95 is the same story. Its impossible to get support from Microsoft for Windows 95 so LabVIEW doesnt support it as NI has no way to test if something is buggy on a non-supported platform.
BTW, if you are refering to LabVIEW embedded this is different beast altogether. This "addon" allows you to directly target embedded processors (kinda like FPGA) but your comparison is faulty. The pentium chip boots into Windows 95 from hard disk so whats on the chip is the *BIOS* and loaders, not Windows. If you *could* run LabVIEW embedded and target this chip it would no longer have this bios (or anything else) and it would only do what you programmed it to do and certainly no longer boot up as you are accustomed to seeing it...