I acquired a collection of cards among which were some sinkholes. One in particular is signed;
I understand the name in concept. From the wiki page for The Duelist:
"Mr. Suitcase" being a reference to the large collections of cards that some players would carry with them
I even found an article by a person asking to referred to by that name on Wizards.com
CALL ME MR. SUITCASE
In the case of the latter I had tried reaching out to the author but received nor response. However given the name of the author is Kelly Digges I doubt that is his signature.
If the former holds true it could just be anybody. I am curious to know if this is somebody? Searching for BuHo didn't get me anywhere.