I don't know if there's any reference to official publications but he's right - you MUST not use the word takeoff until you're cleared to power away and lift off the runway - a point made particularly poignant by the very nasty accident at Tenerife involving KLM and Pan Am 747 circa 1977/8.
I don't even agree with the second point - just don't EVER use the word takeoff unless your hear the phrase 'CLEARED FOR TAKEOFF'. Just to avoid any horrible incidents.
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