So my DH and I just moved into our first house (town home technically) about three weeks ago and we absolutely love it. All of the property is taken care of by maintenance crews and it's run by an HOA. End background
Unfortunately, a guy just moved in next to us about a week ago and he's already causing problems for me. He's been taking the popcorn off of all of his ceilings and he's left an absolute mess on our front walkway all the way up to the front street. I met him for the first time on Sunday and asked him to please clean it up since it's making a mess. He promised he was going to clean it up, but by Wednesday it still wasn't cleaned up so I went to my neighbor of the other side of me and asked her if she had the number of the HOA people so that I could lodge a complaint. While we were talking, he drove up and she asked him to clean it up ASAP and he made the excuse, "I know, I'm so sorry, but we finished really late last night so we couldn't clean it up. A few other people have complained..." and he looked at me pointedly. She said she didn't really care, but he needed to clean it up ASAP as it was against HOA rules.
His way of cleaning it up was to wash it off the walkway into the grass and shrubbery because it'll "eventually disintegrate." Honestly, I'm not happy with how he handled this, but I don't want to become "that neighbor" that complains every time he does something like this. My husband says that I overreacted and that I need to consider the fact that he's going to be our neighbor for the foreseeable future. Am I being ridiculous?
If he does something again where I need to ask him to stop doing something how do I approach him without seeming like "that neighbor?"
I've included pictures of the mess he left.

This is his front door and my front door is on the other side of that wall on the left-hand side of the picture.

This is our shared front walkway. This stuff goes all the way to the street.