By locking their products "in", they're also locking third parties "out". How on earth would they be able to "lock-in" the Apple Watch to the iPhone while at the same time NOT "locking-out" third parties?
I think they're suggesting that lock in implies apple didn't write the code to help support 3rd parties. Lock out implies they actively wrote code to prevent 3rd parties.
With other companies there may be a difference. But with Apple, for all intents and purposes, it's the same thing. Because they are hostile to third-party integration using undocumented API's or interfaces.
It's the same thing.