Extra traffic that their infrastructure can't handle since he fired all the people that knew how.

Like reddit, he also probably sees it as losing millions of dollars for data he wants to be paid for.

So losing money from degraded services and losing potential money from data being taken.

What's worth more - the loss of ad revenue from walled login, or the loss of potential revenue selling the data

Your first mistake is assuming that Elon Musk uses any kind of logic.

There's no way they cause more damage than what they have done now. The vast majority of users (and eyes on ads, etc) are not going to have accounts. The majority of accounts that might pay money only do so because lots of people (who may not be logged in) see them.

Elon doesn't understand how to use robots.txt.

You have to assume flawed logic if you want to understand him.

there is no Elon logic other than having an ego larger than this planet