That's misunderstanding it slightly. You have already retained Silver this year, regardless of whether or not you fly before 8 June 2022.

In any year, whether it's worth flying on trips that you wouldn't otherwise make just to retain Silver really depends on what you want Silver for. Sometimes, it almost seems as if some FTers work hard to retain status so that they can use it on future trips that they will take for the sole purpose of retaining status.