I think it's scaredy-cattiness. Worth considering, but probably just that in the end.
How could they find out about it? Is there a way they could connect your BL identity to your RL identity? I know your pic has been on here - do people recognize you from BL who you've never met in person before?
This character and fitness stuff is typically based on two things: (1) dishonesty -- and by that I mean having stolen, cheated people out of money, been sued repeatedly for fraud, etc. -- and (2) having a criminal record. I don't see that having participated in a harm reduction website could cause you to be accused of either of those.
If you've admitted to using illegal substances in your posts, they would still have no proof of that actually happening. What if you were exaggerating your history just to be cool? What if that was your roommate posting on your account? I don't think they have the time, resources, or inclination to go on a witch hunt.
Then again, I don't know how Kansas does things. In California, they couldn't do something like this. They wouldn't have enough proof, and they can't spend that much time on any one applicant to the bar.