The easy answer is the subject, language used, pictures applied, or the level of aggression used in those posts were too excessive and were noted and removed by one or more mods.
In specific, PMs are best in these situations as if the subject was enough to gain attention and action in public than it would be removed again if brought back up.
That said, anyone here who has posted more than a 100 posts has had a post or two or more removed.
For myself I had a couple removed for...
too sexy or suggestive a picture (girl's butt shot wearing star wars panties...fairly harmless but the family site consideration got it removed)
an argument that got one side hot enough to complain to mods (sigh...it happens, especially among fans, geeks, and nerds we tend to have opinions)
...and more of the same.
One subject that I have not been part of but I have seen many many times is when someone posts about other sabers made by other companies with a direct link to the same...that is not permitted and is insulting to Ultra Sabers as they provide this forum to support their sabers and their fans. These types of post get removed fast.
Most likely if there was an argument that went over several posts between forumites and it was found to be too much then most likely both sides of the coin were removed.
But we can only guess at the particular...as noted contact the mods who removed the posts.
Have a good one!