1). It's an implausible and unnecessary badly thought out piece of pseudo-science pressed into service to muddle a simple and more plausible (in it's vagueness) mystical energy field. If Star Wars was science fiction there would be no sound in space and at the very least the pseudo-science would have been worked out like it is in Star Trek. Star Wars is a space fairy tale, it has mystical energy fields instead of Gods or Genies, it doesn't need microscopic symbionts.
2). Anakin as seen in the PT is a bit of git anyway. He is ambitious, he is wrathful, he has a chip on his shoulder bigger than a small moon, he has a real gratitude problem. Padme is dead (even though she shouldn't be yet according to the OT but I digress) he still has an axe to grind with the remaining Jedi, he still has a very powerful Sith Master to study and bide time to supplant. He may be a cooked torso wrapped in walking leather but he does still get to order people around and inflict his breathing problems on people who disagree with him.
3) Bad pun.
Kenobi has physically got higher ground, an advantage which will render Anakin's leap into a futile gesture of rage resulting in him becoming a robot haggis.
He also has the moral high ground (or so Lucas thinks).
Anakin is the bad guy now and Kenobi is the good guy.
The good guy who exploited Padme's love and placed a pregnant woman right in the dangerzone to get a shot at killing his friend/pupil/ward/her husband.
The good guy who would go on to play the weirdest mind games on Padme's children both while living and as a spooky voice.
But that's how the line is meant to work.