How to find culprit blocking TCP ports 80, 443, and 5223 on macOS?
There are two things you confuse:


FaceTime and iMessage require communication on ports specified in the article for outbound connections.
Your "Permission denied" message is related to opening the port 80 for inbound connections. It's not because of any process blocking it, but if you want to make a process listen on a port less than 1024, you need to use root, so:

sudo python -m SimpleHTTPServer 80