The logic does not prove that something is worth doing, it proves that the one particular argument for something being not worth doing is invalid. "This can lead to hypothetical bad result x" isn't a valid argument by itself, meth is only bad because the badness is sufficiently bad enough, not simply because it is not the healthiest possible choice.
It is a fallacy to assume that if a particular argument is wrong that the opposite of its conclusions must be true. You can easily think everything the blog post says is incorrect and also think hackathons are bad.