Exact wording as follows:
Waterskills Assessment
Before Open Water Dive 2, have student divers demonstrate that they can comfortably maintain themselves in water too deep in which to stand by completing a 10-minute swim/float without using any swim aids. At some point before certification, have students complete a 200 metre/yard continuous surface swim or a 300 metre/ yard swim with mask, fins and snorkel. If conditions warrant, students may wear an exposure suit as long as they are weighted for neutral buoyancy.
I suspect that the interpretation for the float would be that any positive buoyancy from the suit would be classed as a swim aid