I think you're looking at the statement in too narrow a view.

If one just got out of a relationship and wanted time to decompress and be alone a while, they are single by choice. Likewise if one wanted to focus on education or a project for a while and set aside dating to do so, one is single by choice.

In other words, single by choice can be a season. Nowhere is it mandates to be a permanent declaration.

What you said about it not really being your choice because there's no one to date due to standards only applies the way you laid it out if those standards are superficial or you're approaching dating like you're trying to win a trophy. That would be why it's not working out for you. People are not dolls or trophies to be won.

Any time you approach someone with an attitude of what you can get for them without equal or higher consideration of what you can do to elevate them, you're playing a losing game. That's why being generally social works for better than gamer style dating or thinking.