I don't think you even need a viable alternative to make this kind of threat. That's why we used to enforce antitrust laws.
How would you break up Apple in this case? They can’t sell iPhones, iPads, Macs, Watches, monitors (their newest monitor has the same processor as the iPhone 11) and AppleTVs?
Would you break Apple up so each line of iPhones have to be a separate company?
What did they do with regards to TSMC that would be anti competitive? Invest money in a supplier to ensure that it had capacity?