Hi,
You take out the waterbowl mainly to help avoid transfer of any possible RI's
It obviously isn't a perfect idea but it does at least avoid a healthy snake drinking infected snake drool.
Was the previous keeper feeding in tank or in a feeding tub?
I know when I had to convert one of mine from using a seperate feeding enclosure to eating in her rack tub it took her a few feeds to get the idea.
dr del