I also concur that this case clearly falls within the scope of marketing/product-placement.

The use of an advertised product *(Astah)* - **might actually be an appropriate response to a given question and doesn't necessarily warrant a flag.**  Especially if the poster is going into enough detail in explanation and thoroughness with how the product meets the OP's described problem.

THAT BEING SAID, **I believe that the community may be justified in down voting these marketing answers.**

However, I think that for reasons already mentioned (i.e. product is not open-source, is not available from official repositories) - that **alternative responses may naturally be upvoted in relation to the product ads** because they might be more elegant, easier to follow, etc...and perhaps very little needs to be done?...

**My personal feeling is that at least a downvote is warranted with a comment describing the reason** (marketing for closed-source software not available from official repositories, OR EVEN, improve this answer by creating an appropriate [PPA], etc.).

 [PPA]: https://askubuntu.com/questions/4983