I've tested this on 2 machines using both Windows 7 and Linux Suse. On one machine, I can remove a PS2 keyboard, plug it back in, and continue typing. On the other machine, the PS2 keyboard does not recover once the plug has been removed. There are differences in these two machines. Both are several years old. Both are Asus boards but one is an old P7 and the other a Gen3 (Ivy Bridge?). I recall older boards having dedicated PS2 ports for mouse and keyboard and these were color coded to identify which was which. You could not reverse the two. My old P7 has only one PS2 connection dedicated for keyboard use. This one does not allow me to unplug the keyboard and plug it back in. The Gen3 board, however, has a combo PS2 port. It's 1/2 purple and 1/2 green and can accept either a mouse or a keyboard. This is the machine that allows me to unplug the keyboard and plug it back in using either Linux or Win7. The other does not. I'm using the same keyboard on both. It's an old Cherry 1800 that I absolutely love using.
I don't know what your PS2 jack looks like nor do I know your keyboard so it's possible that some combinations work but some don't. I'd be fairly comfortable saying that much has to do with BIOS as well. I do recall that early USB keyboards would not allow BIOS entry during POST. One had to use a PS2 until that was fixed. As well, power options were eventually added that allows "wake on mouse" or "wake on keyboard". It was a BIOS thing. So, I'd say the whole issue is a crapshoot and there are no answers that are always right or always wrong. Hope this helps.