Who is their target market GenX or Millenials.
If millenials it's .io is always a good option and frankly they don't care. I work with them day in and day out and they are more concerned about functionality.
If GenX then yeah perhaps a .com is good but again if the name before it solid and memorable even then it won't matter.
If the product/service is good people will remember it or bookmark it, etc. If they get it wrong, they will remember the second time.
Finally the amount of time and energy that can go into something like this at such an early stage of a company has tremendous opportunity costs. That time is better used building something that works well and solves a do-ers pain.
You can rebrand later