Neither Ben nor I are vs. Neither Ben nor I am

[Winwin2011]

I read the following sentences in Longman English books.

1. But neither Mum nor dad is free to go with us.

2. Neither Ben nor I are good at doing magic.

'
In sentence 1' Mum and dad' is singular, then the verb is singular too. I wonder why sentence 2 use 'are' instead of 'am'.

 

[J&K Tutoring]

Good question!
Swan says: "When singular subjects are connected by neither, the verb is normally singular (as in your #1), but it can be plural in a less formal style.

1. But neither Mum nor Dad is free to go with us.
1. But neither Mum nor Dad are free to go with us.

2. Here, the pronoun I is the key, as the to be verbs are different: Mum is, Dad is, Ben is, I am... If the sentence was, "Neither Ben nor Bill ___ good at doing magic," then we could feel comfortable using either the singular is (more formal) or plural are (less formal). We are rightly uncomfortable having I is in a sentence, so we automatically switch to I are, which is better- we have 'collected' Ben and I into a sort of we. 'Ben and I are not good at doing magic' has more or less the same meaning.