It's probably common enough to be an accepted meaning nowadays, like what's happened with "beg the question". I think the original meaning also lends itself ve

It's probably common enough to be an accepted meaning nowadays, like what's happened with "beg the question". I think the original meaning also lends itself very well to people believing the phrase is "tow the line" since that makes some sense with conforming to a rule. Who knows, idioms are a moving target.