If there were a predetermined hypothesis, then the p-value for that hypothesis would be valid, whatever additional exploratory comparisons were made using the same data.
To put it another way, a valid p-value for the whole experiment would have to be calculated by taking into account how many options the investigators had, and what options would they take, depending on the outcome of their "main" test. This would likely be an impossible calculation to perform, because I doubt that experimenters know themselves what they would do ahead of time. This is why predetermined analysis protocols, which I suspect have been rarely employed in experimental psych, are important.
And every experiment conducted using both male and female subjects has the potential for an additional exploratory male-female comparison.