Answer: Yes, he is correct
Step-by-step explanation:
Considering law cases or any case that has to do with charging someone or an organization, it is always vital to have an evidence of proof to give or show to the law court when making your allegations against the company, failure to do so would mean you're not correct about what you're saying if though you might be right.
The Labor Arbiter is correct because the client has failed to give evidence to prove his/her allegation.