The needs of the mother take priority - and that goes as much for who she doesn't want there as who she does.
No, it's not fair - biology isn't fair. Just as the father could, if he wished, decide as they arrived at the hospital for the birth that he'd changed his mind about having a baby and disappear never to be seen again. Not an option for the pregnant woman.
It is just not equal, not even approaching a million miles of equal and the reasons for that should be absolutely clear. She's given birth. She's been through a massive physical and emotional event and is vulnerable, sleep-deprived and trying to breastfeed.
The father's role in the first weeks is to support and protect the mother. His needs, emotional too, come SECOND. Because the mother's emotional as well as physical health is tied far far more directly to the baby's wellbeing than his. And the baby is the important one.
Putting an emotional need of the father before one of the mother is detrimental, ultimately, to the baby. We've all heard the tales of the family where the deluge of inlaws being given the green light to hog baby, interfere and generally upset the mother have led to PND/breastfeeding failure. The father has put his wellbeing - either for emotional support he wants or his wishes not to have to stand up to his family - above that of the mother. Wrong.
And it's about relationships too. If you're a bossy interfering inlaw, then of course your DIL won't want you in her face when she's just given birth. It's about one of the most intensely personal life events you can have. And the DH/DP who forces that for his own sake is stupid, really - there's more than one post above which details how that dynamic meant the final nail in the coffin for any inlaw relationship. I know one person who felt so violated and disrespected by her MIL post-birth that the rift has never healed. If MIL (and her DH) had shown her more genuine care and respect during that time, she'd have a closer relationship with her grandchild. She never will because her DIL hates her.
The mother comes first for all sorts of practical, emotional and moral reasons and only a truly selfish father would genuinely think differently.