My tuppence worth:
Firstly, sympathy to Wogan's family for their loss; he came across as a genial, harmless kind of fellow. Not my cup of tea, to be honest, but still a pretty decent radio/TV presenter.
As regards Morrissey, He must've been deeply shocked when he heard the terrible news on January 10th, especially as he - like us -had no inkling whatsoever that Bowie had been seriously ill - let alone dying - for the past 18 months. I've no doubt that whatever feelings he had for David, this news probably shocked him tremendously. Like it shocked the world. My own guess is that he feels quite conflicted over his response; a case of damned if I do, damned if I don't. Personally, I've always felt that he deeply regretted the rift that occured, despite the childish remarks he sometimes aimed at Bowie. Hence the far more concilitory tones he adopted over the past few years when speaking of The Starman (and fairness, too, to Bowie for never slagging of Morrissey since The Outside debacle). I've no doubt he was/is deeply saddened by Bowie's passing. We lost an all time great. He knows that.
So why no response? Or even an acknowledgement? Pettiness? Spitefulness? Bitterness? Awkwardness? Egoism? The case could (and has been) argued for those reasons, but I'm giving Morrissey the benefit of the doubt here and say it's a bit more complex than that. He was a huge fan of Bowie as a teenager, they met later in life and forged a tentative, mutual appreciation of one another , which ended sadly with The Outside Tour. After that, it never recovered and Morrissey fell into a childish throwing-ones-dummy-out-the-pan syndrome which was exacerbated further when Bowie chose to remain silent on the matter. I think Morrissey probably regrets some of his remarks and this has been made even worse now, with the passing of Bowie. The reconciliation never happened and sadly now never will. So any tribute at this moment may appear forced and insincere - remember it's barely 3 weeks after Bowie's death. But I bet Morrissey has thought about him and feels both sadness and regret. So, yes, the tribute to Wogan may come across as a snub to Bowie - that's a legitimate charge, and has some foundation to it. But IMHO I just think he cannot - as yet - bring himself to speak about someone who was such a formative influence on him. The conflicting emotions he's feeling won't yet allow a rational, proper response.
In time, he will be asked about the death David Bowie and he will give his response. Till then, I'm willing to give him the benefit of the doubt.
As a final thought, I'd urge everyone to buy or listen to *Blackstar* . It's an astonishingly brave and beautiful album made by a seminal artist who knew he was dying. As Tony Visconti said it was his "parting gift." As for the *Lazarus* video - my goodness, what an heroic and fearless video it is - Bowie's final goodye, made whilst at death's door and in great physical pain, it shows the sheer bravery of the guy - making his own death an art-piece as he bid us goodbye. The final seconds, when he bows he head and stumbles slowly backwards in the wardrobe (his coffin) with a defiant look on his face - as if defying death itself - is one of the most moving things I've seen. Stunning. RIP Mr Bowie, you were one of a kind.