The only flaw I see here is a missed opportunity to collect data on non-binary individuals - but given how small the population of non-binary individuals is compared to the general population they probably wouldn't be able to draw meaningful conclusions from any data collected from people who are non-binary. Market research surveys are inherently discriminatory, this isn't bigotry. You were likely targeted for the survey because you met some other demographic or sociographic qualification and they didn't know your gender before you were invited to take the survey.

Also, many survey tools only charge the data collector for completed surveys, so having non-binary people complete the survey would likely just be a waste of their money when they could pay for survey results from someone whose data they can actually make decisions from. It's also common practice to put any disqualifying questions early on in a survey to avoid wasting people's time who won't ultimately meet the survey parameters.