That's the stupid "lalala I can't hear you" method.

Nope, it is your basic separation of concerns.

OfficeLinebacker did not write HTML::TableExtract, so there is no reason for him to turn on warnings for a module he did not write, regardless of any potential bugs in HTML::TableExtract.

If HTML::TableExtract author wanted warnings, surely he would have added use warnings;

If the input is not valid HTML, fix it.

I doubt OfficeLinebacker has any control over third party html, but it doesn't matter, HTML::TableExtract gets him the data hes after, regardless of any warnings.