Rob,

My opinion is that you should hold the site owner responsible, not a developer that is trying to fill a need.

It's like saying "You made a really ugly skin, you should not be selling that because I may have to go to someone elses site and see it".

The "can't be blocked by pop-up ad blockers" part is just good marketing on Chris's part.  It's not really a "pop-up" in the traditional sense.  It actually produces a web page with content designed in a way that the "ad" floats above the rest of the content.

This could be useful for a number of things including replacing modal a lerts, which are also considered bad web design.

Just my perception, but I think your real objection is to how it is marketed which in turn leads to who he is marketing to.

Maybe some wording like this would better suit you:

Do you find pop-up ads offensive?  Have you ever wanted to attract your visitors attention in a less obtrusive way?
Now you can, and it is really easy with content that is actually part of your web page.
Lots of designs are included to make your extended information blend more pleasingly into your current design.
Here is the best part, your visitors will not need to resort to using pop-up blockers and your message will always be delivered with a friendly option to hide the additional content that responds automatically with a simple click.