Over the past decade, relations within the band have gotten steadily worse, and while we fans can never know everything that goes on behind the scenes, Jon Anderson clearly seems to be the one not interested in performing with Yes, or if he does, it must absolutely be on his terms. From the "Yesfans" website:
Jon unilaterally said "no" to any more studio albums after Magnification, even though Steve, Chris, Rick and Alan were game
Jon said in interview that he left Yes after the 2004 tour
Jon reneged on a mutual plan to reconvene in 2005
Jon didn't show up for a 2005 studio album planned by Steve, Chris, Alan and Rick, with Trevor Horn producing
Jon sold off his share in Yes LLC (yes, he sold his share in the band name to the other members)
Jon, year after year, broke commitments to return to Yes, while touring Yessongs under his own name
Jon demanded to be paid MORE than Steve, Chris or Alan for the aborted 2008 tour
After five years of this bullshit, the others finally blew him off and got someone else to sing. Benoit David auditioned, but supposedly he was originally found through YouTube videos of his Yes tribute band. That was the cause of a lot of jokes and scorn, but really, it actually makes a lot of sense to me. And from what I've heard of the shows with him on lead vocals, there are some off-nights, but he's generally quite good and sounds a lot like Jon, and is getting better.
When Jon heard about this, he asked them once again to wait, because he would like to be with Yes again, but just isn't well enough. He's had health issues over the past several years, this is also documented, but rather than just take a break and get better, he went and set up some more solo shows, and posted on his website that the band touring now isn't the "real" Yes because he's not in it.
He's wrong. Yes has recorded and toured without him (Drama is one of my favorite Yes albums). Yes is not about any one person. If Jon quit the band and sold off his interests in it, he has no say in who or what the "real" Yes is, and should shut the hell up.