Arithmetic time.
The number of possible combinations of 28 letters/spaces is more than 10^40.
“METHINKS IT IS LIKE A WEASEL” is only one of those possible combinations.
The ratio of target space to search space is thus less than 1/10^40. This is about 120 bits of FI according to gpuccio’s definition.
Extending the quote to this: “METHINKS IT IS LIKE A WEASEL TO ME IT LOOKS LIKE A WEASEL IT IS BACKED LIKE A WEASEL IT DOES HAVE A BACK LIKE A WEASEL” gives a ratio of target space to search space of less than 1/10^166 - more than 500 bits of FI.
My python weasel implementation found it easily.*
No doubt gpuccio would say that this is possible because I knew the target sequence. Unfortunately for him it would work just as well if I didn’t know the target sequence - if it was generated randomly, for instance, or typed by some-one else.
*mutation frequency 5%, population 1000, no ratchet, 422 generations.