Community event organizers exist, and it's actually a professional position to have. Setting up big conventions that will host thousands of people requires someone dedicated to oversee everything. I don't have any reason to doubt that
emichaels ('s father? The relationship connection to the account owner is assumed) is a legitimate Event Organizer, but at the same time I don't have a reason to believe him either.
It should be said that Minecraft community has been rocked by a number of scam Minecraft conventions, the worst of which being Mine-o-Rama. While the official MineCon will always be awesome based on its legitimacy, people are beginning to be wary of fan-lead conventions, especially those of a larger scale. I don't want to disrespect you,
emichaels ('s father?), but having someone come out of the blue, offering to make smaller Minecraft conventions despite having to piggy-back on his son's account and lacking any credible evidence behind their abilities? That strikes me as a little more than suspicious.
...It does not take hundreds of thousands to do a smaller Con for a few thousand local people in a city. Takes only about $50K. No problem.
Mojang or Microsoft don't need to approve groups of fans getting together to talk about Minecraft, play games and have fun.
For player reference, both of these things are true.
$50,000 won't be rending out any convention halls for multi-day events like MineCon, but it will host a ballroom, pay for speakers (probably some lower-rent ones. Speaker prices are notoriously overvalued), and offer space for vendors. It won't get you far, but it'll get you something.
Mojang and Microsoft can't really stop a convention from occurring, since it's all fan-lead. However, attempting to claim that your event is part of MineCon, Mojang's/Microsoft's official convention series that has legal trademarks and copywrite, is something they can put a stop to. You can't be MineCon, but you can be a Minecraft fan convention with another name. I highly doubt they will allow you to lease the MineCon property.