The point is that they are still paying money. Calling it a "tax write-off" to the layman sounds like they're just doing it to reduce how much they pay in taxes. I.e. It sounds like tax-evasion/fraud.
His point specifically is that tax write-offs don't reduce how much you have to pay overall. They may even increase it. They just redirect some of it to other purposes such as research instead of paying taxes.