well the best person to ask is the person who set it up, if network port is available then it's advisable to separate it out ..
Most common reason is lack of physical NICs. Clearly not your case. Next in line is sharing the subnet, thus avoiding the need for multi-homed workstations used for management.
It looks like the only way to be sure is to ask the person who set it up or look to see if they documented their reason. It doesn't look like it would be a huge problem to switch it over to the other vSwitch.