I agree with Carol. While it may be amusing to us, it is stressful for Albert. He has no way to escape this intruder so he tries to fight or be dominate over it. He probably thinks it is another chameleon with a red head and yellow horn. If he does not accept it within a few minutes take it out. Captivity stresses them enough without adding to it. You should Google "capture myopathy". I did not know about it before I saw this article but it has made me think twice about how I handle my chameleons.
I'm fully aware of captivity stress and the importance in keeping stress as low as possible, especially in chameleons. It kind of seems a little dramatic to bring up capture myopathy though. Regardless, I had already removed it when I made this post. I just wanted to see if he would realize that it wasn't a threat, but I agree that he thought it was another chameleon in his territory. Despite it's inanimateness, he still felt threatened so I took it out. Just a fun little picture, not everything has to be serious.