He's also alluding to the US president's age, which many consider too old. Even with the gaffes he is renowned for, there are questions about his mental capacity, especially considering the stress of the job. So the idea is something like he can read what is written, but has a hard time when there is no script.
I think much of the population agrees that many of our politicians are too old and that we live in a Gerontocracy. To the extent this is felt outside of the US, for others and their countries, I do not know.