It was one example. I can come up with many others. For instance, try going into a restaurant and playing your trombone. No health risk there but you'll be kicked out. Hell, some restaurants you can't even wear shirts without a collar.
TMC, as a private organization could choose to censor this individual if they wanted. Same as a restaurant can refuse service to an individual who continues to play a trombone it it's dining room. Using TMC as a platform for 'free speech' isn't a protected right.
You next argument makes no sense to me. The sole purpose of censorship is not to infringe on other's rights, (i.e. 'fire' in crowded theatre example) whether that right be to have a nice meal in a high class restaurant, or read a Tesla forum without people trying to scam.
There are no rights (at least in the USA) to reading on TMC without people trying to scam. There are no rights to having a nice meal in a high class restaurant.
Yelling 'Fire' (falsely) in a crowded theater would cause evacuation and possibly panic (and did in the original court case) which ended up with people being trampled and hurt. This infringed upon their rights to not be hurt in public areas. I would classify the 'no shirt, no shoes' rule as dubious in actual health prevention. But me contacting a disease due to others actions is something that the courts deemed I have protections against.
So in both cases my right to not be harmed (either by trampling mob, or contracting disease that is easily preventable) takes precedence over your rights to yell 'fire' or not wear proper clothing.
Also private business, open to the general public, have the right in the united states to refuse service to individuals, but not groups. I can ban "Matt" but I cant ban all "Matt"s. There is some room to debate what constitute a 'group'. "Matt"s would most likely be classified as a group, while 'people playing trombone while eating' would probably not fall under the group classification. I also believe 'people not wearing shoes, and/or shirts' wouldn't fall under a group classification.