The point is that some arbitrary number of weeks of vacation isn't the business-destroying choice this founder makes it out to be. Use your PTO. You earned it.
If you are one of 100 CSRs, then it wouldn't be business-destroying obviously.
Business owners can take this risk but using "don't take more than 2 weeks of PTO" as a risk mitigation strategy is disingenuous and disrespectful to their employees.
Haven't you ever joked about the "bus factor"? All the startups I've worked at would have likely failed if any one of the core people had to depart, for any reason.