You know what never ceases to amaze me?
That these 20 year old "adults" (or at least that's what every thread about a 20 year calls them) are considered adults for everything except anything that might make them remotely upset or uncomfortable. Then they become"just a kid".
In my world, adults can handle uncomfortable conversations without saying something totally stupid.
If I had a 20 year old "adult" child who was bringing a significant other home, I would have no problem saying to both "adult" child and "adult" significant other that they would not be sharing a room in my house. I would expect significant other's response to be "OK".
I am a direct person. I say things directly, and I say them to the person/people who need to hear them. If these 20 year old "adults" can't handle that, then perhaps they are not as adult as they think they are.
OP, giving the guy the benefit of the doubt, chalk it up to nerves and see how the relationship plays out. She wanted you to meet him, so he can't be all bad....