It wouldn't have been so bad if Riot was fully honest from the start.

Riot is a large company with a lot of people doing different things, and a lot of communication issues. Riot does not know what Riot is going to do most of the time. Considering that everyone has to discus all possibilities, before making a final decision, and the PR people are obligated to keep their mouth shut until the decision is final. (To avoid misleading people inadvertently.)

And I'm giving Riot benefit of the doubt. Riot probably had all intent to release SoloQ, only to have their plans faultier on them, potentially though no fault of their own.