Yes, Coinbase limits BTC withdrawals based on current USD value. A lot of traders lost money because they couldn't get their funds out in time. Coinbase will likely get sued and it'll cost them.
Coinbase certainly has conversion limits, but anyone that wanted their Bitcoin into Dollars knew about this limit far before the warning of Coinbase only supporting one side of the split, and converting into Dollars means you don't want to risk the split and you should have been diversifying far before Coinbases announcement.
"Sending to another wallet" IS a withdrawal.