"Non holders" can often have a more impartial view of a stock...

"Non holders" can often have a more impartial view of a stock than someone who has "skin in the game".....their opinion is of value and they shouldn't feel bullied out of having one because their opinion is not positive about a company.........no matter how bad the stock is traveling.
You could ask the same question "Do they believe their one liners will actually convince or influence anyone of anything in their agenda?" about holders of a stock who post on HC..........
If you are serious that you are investigating "why non share holders insist in meddling in threads they have nothing to do with" and why they are "wasting everyone's time in threads that are none of their concern" then you have a problem with impartiality which will affect your critical analysis of the research data.......you need to talk to your supervisor for some advice about your biased opinion on the thesis topic before you continue your research.