There may be more to the story if you are truly interested...
I suspect that Musk/Tesla wanted to help and that they sought out the right folks from whom to get advice. And those folks suggested that they do what they did.
If that is the case he may have stated that he would help with ventilators in the public domain
before he got such advice...
Or he may not know the proper terminology. Who cares?
https://engineering.berkeley.edu/news/2020/04/turning-sleep-apnea-machines-into-ventilators/
https://www.fda.gov/medical-devices/letters-health-care-providers/ventilator-supply-mitigation-strategies-letter-health-care-providers
Likely the Office of Device Evaluation at FDA is busy. Back in 2017 that FDA office was headed by a PhD-- I met his brother back then who was at the time an EE consultant working on project I was leading. The gentleman told me the story of how is ex-college roommate once asked him to help tech cars at an IMSA race in Florida in the 70's. His ex-college roommate was Jerry Woods' best friend. The world is small.
Anyway, yes these types of machines can possibly be helpful... there is more to critical care than just one type of machine, and desperate times call for desperate measures.
I applaud Tesla in this effort.