No - you are completely wrong.
There is absolutely nothing wrong - or even remotely immoral - about paying using invoicing while a company gets going. It's common and normal.
And payroll is not easy - it's a huge mess - and it can be very complicated.
If a founder, with funding, told me: "Invoice us for the first two months until October when we are up with payroll" I would have no problem with that so long as I was getting paid.
Again - of all things, it's not the issue.
The non-payment, the lies about funding, the loans from staff, and all the rest were bad signals.
What's odd is how nobody seemed to have anything to say about the product itself ...