Thanks. I'm not actually the researcher in question but am helping track this down for a PhD candidate who's a patron at my center. I don't think he's doing any comparative analysis between algorithms, rather he's compiling reference information for his works defense where he may very likely be asked, "which min spanning tree algorithm did you use?". The answer can't be "I don't know" or "the one Esri uses" ; )
Esri tools usually post the specific algorithm details on the help pages so I was surprised this wasn't there. Unless it really doesn't matter in practical terms which is used?