Trump does nothing but mock others that have upset him. He makes fun of the way people look, the way people talk, and anything else about a person that he feels is a weakness to them. He is also very quick to threaten legal action against anyone who crosses him, in attempts to shut people down. Trump is a perfect example of what a bully is.
Trump.org could be in relation to Donald Trump or anything else. If it was not a copyrighted term or a domain that existed, Donald Trump has no right to it. People share surnames and many serve as action words, that can be used for something entirely different. Therefore, it seems like Donald Trump was just throwing around his power.
Plenty of evidence supports the idea that Donald Trump is a bully. This particular incident of someone purchasing "ttrump.org" which resulted in a law suit is only the latest in bullying displays from Trump. that being said, a successful businessman is prone to using legal intimidation to safeguard his assets. A website domain name like "trump.org" is a great asset to the Trump brand, especially now that Donald Trump is a political figure on the global spectrum. It's not really surprising that he would sue anyone who dared purchase that domain name.
The man bought the site trump.org about four years ago in an online auction and the domain name could mean any Mr. Trump.
The threat for lawsuit is just because the owner of the site is anti-Donald Trump, so this is typical bullying. If he was pro-Trump, it would have been a different story altogether.