Considering this might very well end up you losing your google account, it is a very necessary warning.
If anything, the author should be more clear about what happens if youtube gets mad: you might lose your google account along with access to mail, drive, photos etc
The warning is fine, the warning while playing Pollyanna is annoying and disingenuous. To put it in a more constructive way - the author should be proud of the hack and all the fun and turmoil it could cause.
I do love these kinds of hacks, but I hate these kind of weaselly cop-out statements. You made the tool, own it!