Indefinite pronouns and the "deadly four"

[Emily Prosser]

Hi:

I'm going through the book (Chapter 4) "the deadly four" on page 63. Does this rule apply to all of the indefinite pronouns listed on page 30?

Example,
"SOMEONE is tapping his/her foot?"
"No one should take his/her hat off"
"Anyone who does not have his/her own hat, should ask me for one."

Thank you,
Emily