When is a WISM Module not Hot Swappable?

We had a couple old WISM modules sitting in our server 6500 switches in our Primary Data centre and our Secondary Data centre left over from a migration to new WISM2s, and our Network admin thought it was time to do some house cleaning of the switches.  So, following procedures for removing the module (Discussion and links can be found at https://supportforums.cisco.com/discussion/11558476/how-remove-wism2-catalyst-6500-series-switch) he proceeded with removing the modules from both our  server switches.

And…..  all network traffic to our servers comes to a standstill.

A reload of the 6500s later and we're back in business, but it leaves us with many questions.  Nowhere did it say that the WISM is not hot swappable, so what's the deal.  So a ticket was opened with Cisco and logs were transferred and hoops were jumped through.  They came back to us with the opinion that the modules were removed too slowly.  The WISM backplane has 3 different length pins, when only the longest pins are touching it pauses switching on the switch.  Apparently removing the module too slow will cause the pause not to be just momentary, in our case a reload of the switches was required.

So, just a heads up if you happen to be in the spring cleaning mood.