Yeah, those instructions have a couple mistakes like that with the wrong line numbers listed.
The spouse is counted in the household size, whether or not their income is used. If they don't want to use their income, then they do not have to fill out an I-864A and agree to have it used. Don't list them as Person 1. Just count them in the household size in Part 5.
The sponsor filling out the I-864 will need to provide a copy of their W-2 to go along with their joint tax transcript, to show their individual income from the return. They should also provide proof of their current individual annual income with letter from employer and/or recent pay stubs.
