Many of the candidates seem to be joke candidacies. For example, TrojanPony's candidate statement read as follows, "I'm just a very nice guy. " Should Wikipedia start preventing these candidacies and block editors who try to disrupt the project?

Only if they succeed in actually disrupting anything, which is unlikely. Contrary to popular belief not all joking is disruptive, and even then not all disruption is harmful.

Even the United States doesn't incarcerate third-party candidates who run for president, even those who are willfully disrupting the election and whose success probability is equal or less than TrojanPony.

There's no need to formally tighten the standards to disqualify frivolous candidates when we can simply choose not to vote for them. Plus some people will just want to raise the bar again and again every time they see a candidate who is patently unelectable despite meeting whatever the current requirements are.

I mean... just look at RFA.