If you do look at KY's link, you can see that the bread there has too dense a crumb.
I thought the same thing, BDL. But the original poster asked about a dense bread. Specifically, what was asked for was a bread that is "sour and heavy." And this one meets those requirements.
I'm glad to see you finally concede that bigas and poolishes are not synonyms, but refer to preferments that have different levels of hydration.
The problem with both those words is that there are technical definitions for them, but many preferments are more or less like one or the other, but not exactly so. The "starter" in this bread, for instance, is actually about halfway between a true poolish and a biga. So, because it's more poolish-like than biga-like, calling it a poolish is OK in practical terms.
But, as you note, the name doesn't really matter all that much.
Sirlene: If you try this recipe, and it's not sour enough for you, let the preferment sit longer. You can leave it at room temperature for up to 36 hours. If you want it even more sour, you'll have to feed it.
But don't assume that longer is better. Try it with 12 hours first. If that's not sour enough, go 24 hours. Etc.