How to Talk to Husband About Sexual Harassment Accusation at Work?

My husband works at a small store and recently had an older woman came in to buy some stuff. On her way out, he was holding the door open for her because she was using a walker. As they were in the doorway, she said something about "Oh no, we're not doing that today" suggesting that he was trying to make some type of move to sexually assault her.

He is really offended by her comment because he is not the type to harass or assault women. I'm having a hard time talking to him about it in a non-biased way, because I know what it's like to have to assume that men are going to try to pull something, especially if you're alone.

I'm hoping to get some advice on how to talk to him to make him feel better or more supported because both conversations we've had, I feel like I'm invalidating his feelings because of my bias.