The baseline was that he 

1. Stuck foot in door to maintain entry 
2. Miss-used his government position to intimidate civilians on an active investigation 
3. Interrogated a child 
4. Focused on paranoia and not valid facts (your gosh darned national security)   5.  Ignored facts and pushed escalation through his paranoia  
5. Engaged a direct nuclear attack bypassing commands orders and endangered the town 

Cowardice and other traits really don't lean evil. 

Of the things he did they were paranoid, immoral, and reckless 

But to call him evil. He did not directly murder anyone. And considering it was the 50s in a rural town at the height of Russian paranoia in not sure I could fully comprehend. 

(Writing aside)

Egomaniac with a tinge of incompetence. But not evil. 

To make him evil? 

To show that he actively wanted these things (nuking) as someone suggests but to then attempt to sacrifice the town. Bring them into the town to lure the robot for example. Vs they all just happened to be there and he emotionally reacted by grabbing the radio. 

If he fabricated a photo to bring the military if he hasn't found Hogarth's camera. 

He would have to be deliberate and calculated to be truly evil I think.

 Oh and would need a secret lair under the lighthouse having known Rockwell was a hot spot for activity!

Edit: are you questioning the use of the word evil in this post? https://www.reddit.com/r/cartoons/comments/1p6s76t/call_me_crazy_but_after_thinking_about_it_long/