lightbrite,
Most respondents to your OP are assuming that the reason you were uncomfortable knocking on his door was because of tznius. In a later post, however, you wrote that you would just ask him what he would have wanted you to do, which suggests that you are fine with having conversations with him (i.e., it doesn’t violate your sense of tznius or safety). Therefore, I am confused about your OP, because I do not understand why you wouldn’t feel comfortable knocking on his door.
Also, what did you mean by,
I don’t want to be the nice older neighbor next door