Nah, nope, nuh-uh, that's not how science works. A person's concerns about the methodology or conclusions of a particular study are not invalid just because they haven't run their own experiments.
It's pretty easy for even a layperson to question this particular study, for a few reasons:
- The sample sizes are very small
- Some men can get erections/aroused if the wind blows the wrong way, or even for no reason at all - putting porn in front of someone and expecting them not to become aroused is a dubious assumption at best
- Using some external test to determine someone's sexuality, instead of using the person's self-identification, goes against the last 30 years of progress we've made in gender and sexuality studies
- The conclusion of the study may indicate some level of homophobic or anti-homosexual bias
Don't gatekeep good critical thinking. Good critical thinking is the only thing you ever need to question any scientific study.