Mistory, you are being his parent and you are making his safety your priority (along with your sobriety. Double priority, right? Right!).
I am so impressed with you because I know how hard it is to say no to your kid, especially when you don't have hard, fast reasons to say no.
I agree that the fact that he didn't want you to call the friend's mom is a sign that you did the right thing. I am not saying he was getting ready to go out and get trashed. I even wonder if he was glad that you said no. Sometimes kids really want us to set limits. I have told my kids that they can blame me for saying no to anything they know they shouldn't do; I don't care if their friends think I am too strict.
Good job tonight, Mom. No need to pick up. You did great!