Am I Being Discriminated Against?

[Scott Trench]

So I'm a house-hacker that is actively offering on a second investment property. I have a bit of land lording experience under my belt, but still have yet to go through any real problems. I've got a tenant in place, and while I still don't know what I don't know, have attempted to educate myself over the past year pretty thoroughly on the ins and outs of real estate investing.

Yesterday, I attempted to rent out a house in a ski-resort town near Denver for a weekend with some friends. The home was advertised on Airbnb, I met the qualifications for the number of guests advertised (10) and submitted my money. 

However, the lady then told me this:

I think we are going to have to pass on renting to you in February. My parents are really new to this, but just don't feel comfortable with such a large group at this point. Its really set up more for 1-2 families than for a large group of friends. 

They didn't specify families in the ad - and my group was clearly within the advertised number of guests. I believe that the reason I was turned down was, "You are a kid, and you are bringing other 25 year olds to our nice place and will trash it. We don't want you." To me, that seems unfair (and illegal?).

Anyways, I'm not the kind to go after this person, just wanted to vent and hear what others had to say about the issue. Is this allowable, fair, reasonable, or what?