I think commentators are kind of funny with Trump. If you want to know Trump, you should have lived with my dad for 20 years, because that is the key. My father was also a sociopath and a narcissist - I get it.
Trump invited the Senate for 2 reasons. First, like any narcissist, he loves making powerful people do what he wants. Making 100 of the most powerful people in the country get on a bus (not even limos!) and drive in traffic to the White House is fun. Next time he'll make them were funny hats and wave.
But more importantly, second, he is freaked out by North Korea. He knew it would be an easy fix. And he knows he is a really really smart guy. So, if HE thought it was easy, then those putzes over at the Senate thought the same thing. So now he will clear this up for them, and explain how difficult it is.
PS - Next time, to prevent leaks, he is using the Cone of Silence. The staff just can't find it yet. He knows it's there somewhere.