Johnny Jacobs was the announcer. Just a few completely off-the-wall guesses (hey, it's almost 2:30 here):
1. They needed a staffer quickly, who could speak clearly.
2. They figured the show wouldn't get a) rerun, or b) discussed 40 years later.
3. They needed a staffer quickly, who came cheap. They would've prolly had to pay Johnny O. or Kenny Williams much more...
Again, all speculation.