That side-effect wouldn't necessarily be bad. Let me explain:

The only possible value you can get from posting a job advert at PM is that there is a high concentration of skilled perl programmers here, and by posting as one of them you bypass several of the negative connotations that come along with other methods of advertising. Case in point, metaperl posted this thread in your defense because he thinks you are "the monkish type", therefore he tends to look at your advert more favourably than he would otherwise.

There is no shortage of ways for you (or others like you) to reach a large community of programmers who are looking for a job and offer them one. There is a shortage of places where you can do so without the immediate suspicion that comes from a job offer without pay (I'm not passing judgement on your proposition btw, there are drawbacks to all job offers, even if it's only the drawback of "having to work"). You saw that the reaction to your node was not entirely positive, many people questioned your business model. I'd bet that if you post the exact same offer to a place where you are not "one of the guys" you'd have received an even less favourable feedback from the exact same people (including no feedback, which is even worse).

What does this have to do with your point regarding trivial posting? Well, if you do post more often (so that your .sig-advert is noticed) people will still read your postings, and if they contain nothing of value you'll be so much less "one of the guys" and so much more a random noise generator and your offer will be viewed accordingly. If your posting instead does contain something of value, the monastery gains and you gain. Win-win :-)