Being "number one" in golf is a function of a rather complex mathematical formula, not the result of winning a recognized championship competition. It fulfills an apparent widespread need for ranking things ... but it certainly doesn't produce any universal agreement about which competitor is "the best" in a given week in a given tournament.
That being said, Luke Donald received more than "an occasional Luuuuuke" from the fans at the Memorial for his efforts. There were holes I watched where the number was closer to fifty than a single beer-enhanced serenader. If Bob Hunter had watched this group come off the 17th green he would have heard a Chorus of "Luuuuuukes". If he were listening.
I suspect if you asked Luke Donald the direct question that he would tell you he was quite pleased with his reception by Memorial fans.