Osage is a damn fine timber, which tolerates knot abuse better than most(especially with a wider flat limb). Locust can be a little weaker in than osage. It has a reputation for sometimes chrysalling even with good tiller.
I find even with backed bows, a pin is a weak area, in compression as well. I used to ignore small pins in backed bows, until I started getting chrysals at these points, in about 1 in every 4 bows that had pins in the belly wood. Since compensating for pins in the newer bows I never get any chrysals. That little bit of extra time and effort gives me 100% chance of the wood having maximised its durability.
Every so often guys post photo's of a beautifully tillered bows, usually a little short in length, or narrow for their draw length/weight, and a couple of days later they post again with a broken bow(usually in tension). The only clue to the break is that it happened at a pin that wasn't compensated for.
Its great that Eric and Slim ignore the knots, and have no trouble, they are quality bowyers. A newer bowyer may not have as much luck due to not having the skills yet.