What's the solution? Not to try to make the two rights mutually exclusive, that's for sure. Tempting, but doomed to failure. That's a road you can only set off down if you haven't grasped the fact that trade marks and copyright are distinct pieces of property. It's easy to get hung up on the way that both rights protect seemingly-identical subject-matter, but the fact is that they don't. In the example cited in the Yale blog, there is copyright not in the cartoon character Popeye but in artistic works depicting him, and if you don't get that you're going to be floundering in the sea that is called intellectual property.
Likewise, a trade mark does not protect Popeye: rather, it protects the trade reputation or goodwill that attaches to the name or image or whatever. A trade mark is an indication of origin, even if nowadays it performs several other jobs - like (as Floyd J remarked at a seminar I went to last autumn) one of those multi-function tools you see in the Sunday supplements which enable you to do whatever you need to do to your bicycle. But the advertising function and the investment function - I can't remember any others off-hand - are linked as much as the source-indicating function to goodwill, so I think the statement at the beginning of this paragraph still holds. The problem is that trade mark owners are trying to extend the scope of trade mark protection, and trade mark offices are letting them get away with it. The problem is one of over-reaching trade mark protection (which is not to say that there's nothing wrong with copyright) and the solution is to put trade marks back in their box.