Who exactly is he getting a "good response" from? When he's included in a poll, he languishes at the bottom. His name recongition sucks. He has nothing that no other candidate has -
If he goes for the "moderate outsider" wing? - Sorry, they already have Pataki, Christie, Kasich, and Rubio to choose from.
If he goes for the "hawk" wing? - Sorry, the field is full of them, seeing that only Paul has been clear and consistent on declaring the Iraq Invasion a mistake.
He can't point to electability - his district is R+1 and he hasn't had a serious challenger since the 90s.
Even on this site, which occasionally embraces candidates with little support from the full primary electorate, he gets a 91% HP rating per my poll series on the republican candidates. No other candidate was viewed that negatively, including those who have lost interest in running such as Rick Scott and Louie Gohmert.
There is literally no reason for Mr. King to run.
Since when is Rubio anywhere near a moderate?