acknowledging a testimonial

Peek does have the power to make clever connections. He once attended a Shakespeare festival sponsored by a philanthropist known by the initials O.C., whose laryngitis threatened to keep him from acknowledging a testimonial.
(Scientific American Mind; Volume 17, Number 3; Inside the Mind of a Savant)

What exactly does it mean?

Thanks.

I presume it means that someone would have offered thanks to the sponsor, but he would not have been able to say anything in reply.