Stupid. Kind of stuff happens all the time in startups. You just put a CFO there with direct report to the chair, then make everything over a certain threshold go through him.
What you do NOT do, is fire your key revenue driver and the very face of your company. That is just stupidity by the board. If he doesnt like having some financial controls and leaves in a huff, that is different but you do not fire them unless there is very serious misconduct.
Again, happens with top sales people, rain makers, developers, etc all the time. Top people are rarely accountants too and as the money gets more, they spend more lavishly. Smart ones who run a company put the controls in place themselves but if not, thats what the board/investors/donors do for you.
Thus - makes me think there is something else going on here. Surely the board could not be that stupid.