I don't remember seeing anyone on Gransnet suggesting we "undemocratically" overturn the vote to leave the EU or change some of the strange decisions made since we left. I assume that is what you are referring to. The country may vote to throw out one government for another government. In the same way, we could vote on our relationship with the EU and decide to go in a different direction. That would be perfectly democratic.
I cannot see why somebody's age relates to how they may perform. As this man has not yet had a chance to show us what he can do, as a local MP, it seems an incredibly prejudiced view, whatever else you say positively.
If someone suggested that a person, aged 60, was too old to do the job, that would be seen as ageist. If you said this in the workplace, you would make the person a victim of age discrimination. However you look at it, it's outright prejudice.