Can't speak for KTR, of course, but assuming Obama said endorsing gay marriage was the "Christian thing to do," I'd say no, it would not be the same at all for several reasons.
First, while I haven't watched that event closely, I'd bet a large sum of money that that was not even remotely all Obama said about his decision making process on that matter. From what I know about it, it sounds like his evolution of thinking on the matter was somewhat similar to my own. In other words, he accumulated evidence and information and experience about homosexuality over a long period of time and then based his conclusions on the facts as he saw them, not on what might pacify those whose attitudes are along the lines of "Crucify them! Crucify them!"
It may well be that political events, notably the public remarks of Biden and Duncan, spurred him to make his statement when he did. Part of what any smart politician does is to consider the best time to make controversial statements about anything at all, right? And sometimes events make the timing of taking various stands less of a choice. For me, the far less admirable possibility would have been if he had made any other statement, because then I would have felt fairly certain he was pandering to the worst "of our angels" rather than doing the right thing.
Second, for a large number of Christians (maybe one or two will even chime in here), ceasing to discriminate against gay people in any way, shape, or form IS the Christian thing to do, and they base that view squarely on the teachings of Jesus, the teachings of whom all Christians claim is their guide, no?
(But for others, I think the difference may be that it's so much more fun and comforting to scapegoat based on the views of the ancient Hebrews and the pious Jewish guy who had a vision during his hike up the dirt road to Damascus! )
Third, one much under-appreciated role of the president is that of "educator in chief." Obama has concluded that U.S. laws should stop discriminating against gay people. Therefore, subtly suggesting that the citizens who most want to continue that discrimination, that is, many of his fellow Christians, might think some more about it, especially vis a vis the teachings of Jesus, is part of his job.
As for Kurt Wise, I'd say he is certainly is a sad person, but I think what Mormons teach and claim and do is different and of much greater concern. Me thinks believing that God directly speaks in your ear (or your stomach) and tells you what to do in specific situations, no matter how insane or illegal or vicious, is a greater pathology (or dishonesty) than simply believing in a fantasy against all evidence and education. And I think that despite being very aware of how much damage the latter has done to humanity, only a tiny fraction of which involves discrimination and violence against homosexuals.
Again, I recommend Under the Banner of Heaven to get a sense of exactly what I'm talking about.
Those who know the most of nature believe the least about theology. - Robert Ingersoll