Um, Penn was actually a lot nicer to the Indians than most colonists or colonizers. He was a Quaker, after all, and a good symbol and inspiration for America.
I don’t know what of this applies or not to Penn but the early Quakers in North Carolina were opposed to slavery and still became slave-holders. The reason was that the fugitive slave laws made free slaves subject to mandatory re-enslavement in some jurisdictions. The Quakers would “buy” their freedom in Virginia or elsewhere and then they would be captured back into slavery as their legal status was only as property.
To remedy this condition, North Carolina Quakers would “own” these slaves that they had bought for future manumission until such time as they could get them to Indiana or such other areas of the Northwest Territory areas where slavery was not permitted. This is why so many town in Indiana have Carolina names, given by Quakers moving there with blacks to free.