I'm an interior designer, so someone more educated on structures than I am can correct me, but it looks like there may be a load-bearing post at the peninsula?

In the original plan, the wall between the cooktop and the original pantry cabinet is shown much thicker than would be required just for cabinet support.

Also, it doesn't really make sense to remove the original pantry cabinet, but leave a non-structural column and spend the money to finish it out. I suspect they would have removed the whole thing in the original renovation if they had been able to. If you're sure it's not load-bearing, maybe there's some plumbing or mechanical in there that couldn't be easily moved?