I wouldn't be overjoyed, but if I knew I just kept someone I cared about safe from going down for something they didn't do, I would do it 10 million times! I would feel so relieved that I could solidly say she was there and we were taking selfies and posting them, so the time frame is definite. Or whatever! In Carlesha's case right now, we were discussing how lucky it was that the video captured it all or her boyfriend would be getting endlessly questioned. Similar situation! If he was her actual alibi, it would be a "I am sooo glad you were here and I can vouch for you! Otherwise, they would be looking at you, too!"
You would be mad to be available to prove your friend's innocence? If she had no idea that coming to your house was going to put you in the mix? If she had no idea she was going to be in the mix? If she had no idea that there was any mix going on anywhere in her world? There are so many things I want to say, but I will refrain so I don't get snipped for being snarky.