it has been recognized by a respected authority on thermodynamics, Max Planck, that the phrase 'entropy of the universe' has no meaning because it admits of no accurate definition.[1][2] Kelvin's speculation falls with this recognition.

The fact that Max Planck is a respected authority can't be easily disproved and he's cited.

On the other hand he did write that more than 100 years ago.

The introductory section doesn't contain any modern physics but 19th century views. If you would gather more modern sources, you might use them to update the article.