I would not take offense at that statement. The actual comment in question was:
I do mention that it is unkind to waste anybody's time, and interviewing if you have no intention of taking the job - lying as you put it - is wasting somebody's time. Besides of course he is really available for work, unless his parents are filthy rich everybody needs some form of income.
First of all, the author of the comment is not really talking about you and is not suggesting anything about your parents. The subject here is everyone, not you. The comment simply states that everyone needs income unless they are being supported by rich parents. It is not in any way suggesting that you do or do not need income or have such parents.
That said, and contrary to @EdwinAshworth's answer, filthy rich carries no negative connotations for me other than the concept of being extremely wealthy. This may itself be considered offensive by people but as far as I am concerned, filthy rich does not imply any kind of dishonesty. At least, no more so than extremely rich or similar phrases. This is supported by the definitions listed here and here.
So, the only negative connotation of filthy rich is that one is too rich. So much so that it is considered excessive. For example, somebody who owns 3 houses and 5 cars may be considered rich. One who owns 15 houses and 100 cars would be considered filthy rich.
However, Edwin tends to know what he's talking about and you also seem to have found a definition suggesting that the term has negative connotations so I guess it must have in certain dialects or contexts. I certainly do not read it as being intended to be offensive in the comment you are asking about however.