The only thing that matters here rather than the nonsense hypotheticals is that they are right, the library isn’t C89 as pointed out by others. This isn’t about

The only thing that matters here rather than the nonsense hypotheticals is that they are right, the library isn’t C89 as pointed out by others. This isn’t about not liking C89 flavor ice cream, but calling it C89 when it isn’t. Like, of all things why mislead about that? Very bizarre behavior from the OP and these comments. The more reasonable discussion then becomes: fix the non C89 issues so the statement becomes accurate, disclose that it uses extensions, or as some have constructively suggested consider just targeting C99 rather than GNU89. Not sure why you think criticism of something not being what it claims is inappropriate.