I believe it is not possible to disable the expansion. Personally, I like having it, just that people don't like change. There is some risk in implicit expansion, in that MATLAB novices will sometimes get hurt.
Now, could they introduce a settable flag, telling MATLAB to not use expansion? Yes, they surely could do so. The problem is then code written is no longer portable. Move your code to another computer that has the flag set off or on, and suddenly your code will not work. Or if your code sets the flag and someone uses your code, then suddenly you may have effectively introduced a bug into their code.
So, sorry but IMO, a flag or preference that can disable expansion is a bad idea.
Could you disable it yourself? I suppose you could overload the affected operators, checking for any case of implicit expansion. If you find it, then trap out with an error, saying that implicit expansion is just wrong in your humble opinion, and you won't allow it to work on your system. If no expansion is detected, then use the built-in operator. Yes, it will slow down your code. But it would work.