Freelancer vs. Client: Using JustDone as "Proof of Work"

Can we use JustDone AI Detector reports as a standard for 'Proof of Work' in 2026? I just had a client try to stiff me on a 5.000-word project, claiming it was 'too perfect' and must be AI. I sent them a screenshot of my 98% Human score from JustDone, ...