When you're a boxer, do you want to hit the opponent once really hard, or a few times with less force? That's really the difference you're referring to. (Note: I'm not a boxer and I don't know the correct answer to that question.) I bolded one sentence above, and I disagree with that.
Tesla currently has a bit over a billion shares authorized, let's round that off to an even 1 billion. Pretend that the stock price is $1000 at the time of the split, for easy arithmetic.
According to
Ihor Dusaniwsky, 24.55 million shares shorted, let's round that off to 25 million.
Scenario 1: 2:1 split. Tesla issues another 1B shares for a total of 2B. But 25M people have shares that they think they own, but are really borrowed by the shorts. Stock price halves, to $500/share, shorts have to spend 25M * $500 to make those guys whole; that's $12.5B.
Scenario 2: 20:1 split. Tesla issues another 19B shares, total 20B. Price per share goes down to $50. But now the shorts have to come up with 25M * 19 shares each * $50, which is $23.75 billion.
So it hurts the shorts almost twice as much. Asymptotically, TSLA could split 500:1 (any more and NASDAQ might delist them if the stock falls below $2 for an extended period) and it would hurt the shorts almost $25B.