Per that article I posted, it actually quoted him as saying "I'm done... I retired." It may have been an informal retirement but that was the decision. You don't formally announce your retirement if you don't think people will care. Who would he announce it to? Most Filipinos don't even know his name, and the figure skating community in general wouldn't really care too much since he's not a top skater. All he needs to do to "retire" is just drop out from the scene.
It may not have been a wise decision, but I feel he lost motivation. He had been told a few weeks before that it isn't happening and all the countries had confirmed their slots. Even previously, he was well aware that without a quad, and being from the country he's from, he's unlikely to get anywhere. Again, it's been an uphill battle. Figure skating is a difficult sport as it is, try doing it with very little support from anywhere, coming from a country with no snow, which struggles with bigger problems, and coming also from a non-figure skating family. I had wondered before what motivates the lower-tier skaters to continue on with this difficult and expensive sport, so it's not surprising that they lose motivation.
Makes me recall the discussion on the team event, how it's biased towards certain countries. News flash: Figure skating itself is biased towards certain countries. How often do you get medalists from countries without winter? Or less well-off countries where figure skating is an impractical sport? This is another reason why Denis Ten is someone to admire. And also part of the reason why I'm now heartbroken that he didn't make the free skate.
Well, that became quite long.
And to the person who apologized that they like Shoma and want him to medal, don't apologize for liking anyone. We like whom we like because we like them, you don't need to apologize for it. You don't need to justify it or have a reason for it. Figure skating is a sport, and also an art- and which art you prefer is a personal calling. Which skater you like is personal and emotional, and there is no right or wrong answer. You shouldn't let anyone influence you in your decision.