I don't understand this example. 

> importing re.match directly into __main__ replaces the keyword with the function. 

It has not replaced anything, if you do a match statement it works and doesn't call your function. For example:

>>> x = [1,2]
>>>
>>> def match(*args):
...    print("Oh no")
...
>>> match x:
...    case [y,z]:
...       print(y,z)
...
1 2

Here "match" when used as a statement has not been replaced by the function that prints "oh no" so the match statement works as expected and so does the function:

>>> match
<function match at 0x7f7c173c5ff0>