The safety issue seems like an odd thing to raise, since the US has more floating reactors than most other countries. I don't recall it being raised when Rickover was designing the first floating reactors in the early 1950s. Of course, perhaps its because most of our floating reactors only float some of the time and spend most of their time submerged. Globally, there are floating reactors in aircraft carriers, icebreakers, and submarines. Our 9 nuclear cruisers have all been retired.
