と may mark a subject being compared. As for 似る, ～に似る and ～と似る are possible but slightly different. と in this case marks one side of a mutual relation(ship) whereas に only shows the standard of comparison. They both, though, make the second person the basis of comparison when the pattern is XはY｛に・と｝似ている. Consider the following:
31c. その子はお父さんに似ている。 〇
31d. その父は息子と似ている。 〇
31e. その父は息子に似ている。 X
The child resembles his father.
I don't understand why 31e is incorrect. It seems like it is wrong only because of the relationship between 父 and 息子 but wouldn't that also make 31c wrong?
To be honest, I still don't understand the distinction between the two particle uses (bolded sentence in the quoted section). When you compare
Y naturally become a "standard of comparison""? Does に also work with asymmetrical relationships? When you say
X is similar to
Y, aren't you also saying that
Y is like