It's called simple psychology. Any Sith would do it. And Sidious did, in fact, revel in his engagement with Yoda. He was laughing at Yoda's pathetic attempts to defeat him. He was enjoying himself. He had the most powerful Jedi in the palm of his hand. He needed to only close his hand to crush the small Jedi. But he didn't. He could have, but he decided to prolong the small Jedi's suffering.
This is simply getting ridiculous. You claim now to know so much about Sith psychology that your interpretation of a Sith's act can be claimed to be facts?
Dude, you're the most far out person I've ever met.