The "gender is a social construct" thing is an ongoing debate in the trans community, so it's just as likely that two people are saying two different things as it is that one person is being a hypocrite, but it's probably likely that some people simply haven't thought it through enough to have a coherent opinion (which is fine--not everyone thinks about this on a regular basis and no one should feel obligated to).
Just as a general comment, I do think it would be beneficial if there was more understanding that 'social construct' does not mean 'this thing is not real'. A social construct is absolutely real; that's the point. The foundational text, after all, happens to be called
The Social Construction of Reality...
