This could be made to not be a counterexample by using a theory of probability that uses surreals.

That is Pr(irrational|random form 0 to 1) being 1 is of the "almost always" kind, which can be separated form the kind of 1 that is of the "always" kind.

for ω that is larger than any surreal that has a real-counter part, there is a ɛ=1/ω.

Taking only finite samples out of a infinite group makes for a probability that is smaller than any real probability that could well be represented by real/natural multiples of ɛ.

Similarly taking only countably infinite samples from a group of uncountably many samples would result in a probability larger than 0 but smaller than any real value.

Thus we could have P(irrational|between 0 and 1)=1-xɛ and P(rational|between 0 and 1)=xɛ that would sum to exactly 1 and yet P(Z|0-1)=xɛ>0 ie a positive probability.

Similarly the probability of a dart landing exactly on a line in a dart board is "almost never" ie 0 yet that place is as probable as any other location on the dart board. It would be possible to find a dart exactly on the line, you would not just expect to encounter it in a finite number of throws.

However there are counterexamples where all As are indeed Bs but no implication is possible.