(I invoke my pedant-pass.) As formulated in the title, "How many floating-point numbers are in the interval [0,1]?" you could argue that this is the cardinality of the Real Numbers. What the article says it is really talking about are single-precision IEEE 754 floating-point numbers. However, I could define any number of my own floating-point representations at various sizes. The cardinality of all possible floating point representations would be the same as that of the real numbers. This is true even for irrational numbers, as one could formulate floating point representations that specially represent those numbers.
(Also, this is arguably an exception to Betteridge's Law, and arguably not an exception to Betteridge's Law.)
(Also, this is arguably an exception to Betteridge's Law, and arguably not an exception to Betteridge's Law.)