I wrote more about this in the past, but even bookkeepers have been held personally liable. The government considers employment taxes to be paid by the employee on the date the employee receives his or her paycheck, and the employer is merely holding on to that money temporarily. It seems quite unwise to fuck with this.
more examples here: https://news.ycombinator.com/item?id=8081173
I have direct experience of this - I even chaired a share holder meeting about a refinancing.
Most of US payroll is on a biweekly system, so it's hard to accummulate too much liability as far as employee payroll goes.
You can float a lot of other bills in various ways, but if a company gets to the point of not being able to make payroll, it's basically game over.
In practice one way to handle this is keep one payroll cycle's worth of liquid cash "locked up" in an account that is reserved for payroll and which you don't dip into for other expenses. So even in the worst case the last paychecks can be sent out before shutting down, if you avoid the temptation to dip into that account "just this once". That does require having a little bit of a cash cushion, but a VC-funded company should be in a relatively good position in that regard.
If there's no personal liability, and the CEO is otherwise looking at bankruptcy, only ethics would force them to be honest with staff about being unable to make payroll. Employees would be out 1 pay at least, probably more, depending on how well the CEO can lie.