How extensive is the planned paint job? Color change?
Are you planning to remove the windshield & rear window trim? Window seals?
It is not necessary to remove the headliner unless you are planning to paint the interior of the roof, as BigJim mentioned.
I have done an extensive paint job with a color change- removed trim pieces, seals, AND side window seals & retainers. But did not have to remove the headliner, as I did not repaint the roof interior.
Here's the 'before', 'during', and 'after' photos of an extensive & color change paint job.
Neil