"in Boolean contexts, a time object is considered to be true if and only if, after converting it to minutes and subtracting utcoffset() (or 0 if that’s None), the result is non-zero"
Changing at this point would possibly break code that relied on documented library behavior. That's not a responsible thing to do.
Simple is better than complex.
BTW, do you know the original author of the Zen of Python has posted to this very dicussion (while also being the orginal author of said module):
https://mail.python.org/pipermail/python-ideas/2014-March/02... https://mail.python.org/pipermail/python-ideas/2014-March/02...
The "if timeval:" case may contain fewer characters, but it's less explicit. Being less explicit opens it up to greater ambiguity. Ambiguity is a form of complexity. Complexity is the opposite of simplicity.
The explicit "is not None" check may require more typing, but it's far more explicit and exact. That means it's much less ambiguous, and thus less complex, and thus exhibits greater simplicity.