I did some digging and had a few exchanges with @ptomato and @GrahamNelson. It appears that the inform suite of tools will be undergoing a licensing change overall and the banner requirement is dropped.
Here is a quote regarding the banner text:
The game banner requirement will be dropped, and may be
considered instead as a sort of customary courtesy without force
of law, and which would not apply to works where it is
impractical.
Here is a quote regarding future licensing changes:
The change in question is that with the open-sourcing of
Inform, which is overdue but drawing steadily closer - it's
my main activity now - the whole suite of software tools will
go under the Artistic License 2.0:
https://opensource.org/licenses/Artistic-2.0
In particular, see:
(1) You are permitted to use the Standard Version ...
for any purpose without restriction
There will be an explicit clarification in addition to that
which says that works produced with Inform are, for the
avoidance of doubt, the property of the user creating them.