The results aren't the same though. If you want maximum total income and you'll take a percentage cut of one of two salaries, you'll take the cut for the lower salary. If you optimize for maximum income per hours worked, you'd take the cut on the higher salary.
Oh I re-read the comment again and realized they are suggesting part-time lower-income PLUS paternal leave higher-income. That's weird on multiple levels: You want, as you said, optimise for total income; and you want to spend as much uninterrupted time with your kid as possible.
This option gives you neither.
Rather, I have a colleague who took paternal leave with their partner and afterwards switched to part-time for a bit.
