I'm going to intentionally cockblock my friend
Why would you cockblock your friend?
Because I don't like the person they are trying to get with.
When you meddle in other people's business, you are involving yourself in a situation where the outcome doesn't fall on you. You should leave your friend's social life to them and not interfere in it.
I'm going to interfere with my friend's social life, since I don't care if he is single or not.
It's understandable that you don't like the person that your friend is trying to talk to. But if you intentionally block them from talking your friend is going be very upset with you. If you have an issue with who they're talking to you should talk with their friend and try to give your point of view.