It depends on what one means by "sourdough." Some people tend to restrict that word to a particular bread style, usually associated with "San Francisco sourdough" or some variant. That bread tends to be a lean somewhat crusty bread, with sourness varying from noticeable to somewhat pungent.
But others use the word "sourdough" just to connote the use of "natural yeast" (as opposed to bakers yeast). If your source was using "sourdough" in that sense, it's perfectly possible to make all sorts of sweet breads using natural yeast. It was actually the standard way to make such breads before the widespread use of commercial yeast.
If you are going to do so, besides possibly adding sugar or some other enriching agents to match your memory (milk, butter/oil, eggs, etc.), I'd also recommend efforts to "tone down" the sourness in your starter. Traditional French methods for natural yeast sweet breads tended to work on a multi-stage building system, where you'd start with a remaining hunk of dough from a previous batch (the "chef") and then gradually build it up in anywhere from 2 to 4 stages to the final dough size. Each build would range from an intermediate to large dilution of the starter (to dilute any residual acidity in the starter), and you'd start the next build before the previous one had a chance to turn sour.
By doing this, you maximize yeast growth (which occurs earlier in the sourdough cycle) while minimizing acid production (which makes the bread sour). After a few such builds, you'll have knocked down the bacteria population -- which lead to sourness -- enough that the rising of the final bread will mostly be just yeast activity. The final bread is often more flavorful and complex than produced with bakers yeast, but won't have distinct sourness.
Also, this multi-stage method is less necessary if you are baking bread on a regular basis, like a bakery might do daily. As starters sit for longer periods without feeding (more than a few hours), they will accumulate more acidity.
As moscafj mentioned in comments, the baker likely changed something in the process or recipe. If the general question is why big holes happen in lean artisan breads sometimes, there are several possibilities, some of which I enumerated in answer to a previous question.
In very general terms, the more bread is "handled" during the process of a rise, the more even the crumb will be. (That is: "even crumb" = very fine small even holes.) This can involve additional kneading or folding or "punching down" periodically during the rise. The most relevant, of course, is handling and shaping before the final rise where the final air bubbles develop.
The baker is correct that many "artisan bakers" value a texture that has large (often irregular) holes. And many consumers like that. It may not be great for sandwiches, but that is not the only use for artisan bread. If, however, the holes are not evenly distributed but are gathered in certain places (like the middle of the top of the loaf, as you mention in the question), that could indicate inferior kneading or shaping technique, as well as perhaps an overproofed final dough before baking.
Best Answer
From what I can tell from the picture, most of the white stuff is flour; it was likely like that when you bought it, but only you & your memory know for sure. The non-bread & non-white occasional spots in the picture appear to be the olives.
Overall, unless you spot obvious mold, which is more often green than white, I think you are OK to consume it. But it's nearly a week past its date, so I'd consume it soon.