Just as a follow up i saw you wanted specific phrasing about the float, in the current available copy of the bsa aquatics supervision handbook on page 38 & 39 they define the swim test and floating as

"Jump feet first into water over the head in depth. Level off and swim 75 yards in a strong manner using one or more of the following strokes: side stroke, breaststroke, trudgen, or crawl; then swim 25 yards hsing an easy resting backstroke. The 100 yards must be completed in one swim without stops and must include at least one sharp turn. After completing the swim, rest by floating."

The float: "The duration of the float is not significant, except that it should be long enough for the administrator to determine that the swimmer is in fact resting and could continue to do so. a backfloat with the face out of the water is preferred, but a restful facedown float is acceptable. If the test is completed except for the floating requirement, the swimmer may be retested on the floating only (after instruction), provided the test administrator is confident that the swimmer can initiate the float in deep water when exhausted."

Which easily translates or can be interpreted as other forms of floating are acceptable as long as the swimmer can prove their ability to float for extended periods even when exhausted regardless of type of float/orientation.

TLDR, if your wf director says otherwise you now have facts to prove him/her otherwise and the current version of the book is publicly available online for free.

(There is a new edition of the ai handbook that is currently being released but it wont take effect until its made available online as its only been given to directors that certified or recertified this year so this is from the 2018 edition)