No, the cellular iPad and other devices are indeed proof positive. The exact same cellular window solution could be applied in a redesign of the MacBook. No one is disputing aluminium blocks radio waves - the dispute is your constant argument it can’t be done because it would require a giant RF window - there is no reason a future design can’t neatly incorporate an antenna system, just like it has been done on many other aluminium devices - including iPads, iPhones and Apple Watches.

Having built 5G systems for hobbyist computer boards (Pi etc), the antenna required is not so very large either.

A MacBook is not and has never been a seamless block of aluminium - there are plenty of design choices to be made to help hide or minimise any antennas.