I have been hot swapping cards since I first touched a Toshiba system several years ago. So far only issue has been a voicemail rebooting when the card next to it is installed. Since I was curious, I looked through the Installation manual:
"Toshiba recommends turning the power supply be Off whenever possible when removing or
installing the other PCBs"

The line before that one:
"WARNING! The power supply must be Off whenever removing or installing the
processor PCBs."

Seems to me like thay are saying that you can hot swap, but power down if possible.