I have sprouted a bunch of osage seedlings in the past using seeds from the straightest osage I could find. Bottom line, the seeds will not grow as true as the parent.
I would transplant seedlings to gallon pots and let them grow for a year before selling them, giving them away or planting them. I found that only about a third would grow straight, the rest would quickly growing like typical osage, doglegged, bowed and twisted. I always culled the inferior seedlings.
Thinning a seedling patch won't make any difference, leaving them thick won't make them magically grow straight. If you transplant them to thick woods you might get a few straight trees but my findings are that they won't grow well in shade.
The thick straight patches of osage trees were planted or seeded at the same time and made their own thick grouping.
I suspect osage seeds are like apple seeds, you can't plant a red delicious seed and expect a red delicious apple tree. I understand there are 13 possible variants in the seeds from one apple tree. I have found osage seeds to be very inconsistent in their progeny as well.