I guess anyone is within their rights to be sniffy and offended at anything they want to be sniffy over, but it's not worth causing a fuss over.
It's reminds me a bit of around a decade ago when me and DH bought a car, (we only had the one car then and shared it.) A week after we got it, I went to the beach with the kids, and DH's mate said to him 'did you let her drive it?!'
Now THAT fucked me off.
I said, 'did he let me drive the car?' It's OUR car, not his.' And he said 'oooh, time of the month?'
Misogynistic cunt.
Also, when me and DH are shopping together, he likes to pack, and I have lost count of the amount of times some (usually middleaged) female checkout operator says 'got HIM well trained haven't you?' We used to say something back, but we just ignore the ignorant sexist bints now when they say it, and talk amongst ourselves. (Well, why shouldn't we? 2 out of 3 times we go to a checkout, the person serving is chatting to a colleague about fuck-all to do with work and ignoring us anyway!)
Back to the OP, the MIL would not have meant to demean the DH. It's like people getting sniffy and offended at the 'Black lives matter' thing, and saying 'ALL lives matter!' Saying black lives matter is not saying ONLY black lives matter. It's just saying the lives of black people are important and worth caring about; it's not saying that white people are irrelevant.
So praising the woman who has gone through the pregnancy and birth, is not ignoring or demeaning the father of the baby. And it's a bit precious to think it is. And let's face it, the woman DOES do all the work. All the man does is sit there, watch tv, look through his phone, read, and eat. 