That's not its only justification. Splitting infinitives often muddles matters, and clarity is a good. You can break the rule, like any rule, if you know what you are doing - but this example is of a bad breaking. It's likely that "not skating", in the apparent sense of active refusal or prevention, is not what the writer used to do. Notice how adopting either of PJ's alternatives clarifies the problem of negating the statement.