IMO this is not a must. Before making any decision in that regard, the real needs and consequences are better considered. What real need drives the requirement for them to have ISO 13485 certification? Perhaps ISO 9001 would suffice instead?
Agree ...

Why I recommend to orangeisenergy is for the following reason.
1. The question is with ISO 13485 standard as the basis
2. They are on the product label and are ISO 13485 company
3. Significant processes are outsourced, and the QMS status of that company is not clear. It is however clear that they are new to manufacturing
4. Evaluation and selection criteria of the manufacturer is perhaps the ongoing association in design and development. No evidence of any other criteria
5. Information about quality management system requirements in purchasing is not evident to me
If the regulatory requirement is the US FDA, then ISO 13485 or ISO 9001 is not a requirement for either of the companies. Yes, perhaps ISO 9001 would suffice, but just an other few steps will take them to ISO 13485.
ISO 13485 certification mostly is from the business risk based decision.