“Unethical” would be YouTube freely allowing monetising of videos with pirated content. As of now, the (semi-) automated ContentID system is their main tool for filtering unlicensed material. Unfortunately, the way it works in practice, there is no way to clear claims prior to upload. There is, however, a method that some users may find useful, where the video is uploaded but “private” or “unlisted”. The copyright claims can then be dealt with prior to making the video “public”.
As authors of music frequently used on monetised YouTube channels we’ve come to learn that a big part of YouTube exposure comes from having fresh uploads. Therefore it is unfortunate that there is no way to steer clear of claims ahead, except for the whitelisting of entire channels, which is considered in special cases.
My advice to you would be to get in touch with the author of the copyrighted material, and ask for a whitelisting of the video (which will be processed by the ContentID partner in question).