I thought they removed mention of any competitor... this is different though.
Davo and I used to write extensions for MMF 1.5. I myself wrote about 18 extensions under the alias "Tigerworks" (listed here), some very powerful with a great deal of work spent on them. I did it all voluntarily, for free. (I did get a free license and a small gift payment after finishing Iso Grid 2, though.) Eventually we got frustrated with limitations in making extensions and got started with our own editor, Construct Classic. Despite all the work we'd done for them off our own back they took serious issue to this. I suppose they wanted us to keep doing voluntary work for them instead of giving them a new competitor.
Anyways at the time this went down badly: we were young and immature at the time, so we had a certain amount of insensitivity and bravado about starting our own project. I regret that we didn't handle it well, but on the other hand, neither did they - threats were made against us, and it was a pretty bad time for all.
Since then there's always been some tension. It's a shame, but at the end of the day all we want to do is write good software, and competition makes everyone work harder, so the users win. It's also made worse by users of either program stating strong opinions (read: being involved in flamewars), so please be careful about what you say about the subject, either here or on any other website. It was all over long ago so there's not much new for anyone to comment on - everyone's heard it all before. Also, they're free to control their forums as they see fit - if they don't want posts about competitors on there, well, they don't have to.