It is until they prove it isn’t, which they might not be able to do. Many trusted 23andme only to see private data stolen. Make the company prove the security in place and the methods ensuring privacy, because you’ll essentially be liable for any failures of the system from a lack of due diligence.
I think the issue is moreso that you’re sending confidential health data to a 3rd party, which is where you lose control. You don’t know the intentions of people looking to steal that data, and you need to consider the worst possible outcome and guard against those. AI training is just one option. Get creative, what could you do with a doctor’s voice and their patient’s private medical history?
Simplest solution is to stop the arrangement until the company can prove data security on their end or implement an offline solution on local servers not connected to the internet.