Correct, in any specific case. But Apple's playing a repeated game, and any given customer is playing a one-time game. Apple can reap the deterrence benefit in future cases, but the customer doesn't really get any reputational benefit from playing hardball, and so has to evaluate the wisdom of suing or not suing based on the outcome of just the single case at hand.
Having the howto guide on Reddit definitely makes it more difficult for Apple. Independent service shops, opening the case, taking some pictures and sending it back to the customer for a flat rate would tilt it even farther in the consumer's favor.
It's supposed to be a scare tactic, like how Walmart always sues people who steal more than $20. The point isn't to make it more worthwhile in the one case, it's to scare off 1000 other people who would otherwise do the same.
It's more like a fraud against consumers than a scare tactic. Walmart is being robbed, trace amounts of moisture doesn't mean Apple is being robbed they've just invented that condition and threshold as an excuse to not service warranties. They have a rich history of requiring legal action before respecting consumers rights, even to fix their own mistakes.