I don't give a fuck about the slave bad/politics stuff, so imma only "attach" my 2 cents to the part that talks about this manga:
I kinda disagree with the "you pissed me off so imma fuck your mothers" bit. Dude loved the moms even before he and the rest of the kids left the village to be "hero team". He saw and treat them like his kids, cause he is mentally 40 some dad that already had his own kid before he got isekaied. The 25+ girls in this magical world are what is on his radar, and what in that world is considered "used worthless goods".
When kicked he just accepted it as "kids rebellion of sorts" and gone to buy a slave and found his oshi mom there, so he got her, then under her "patronage" he got the rest of the moms. Sure if she wasn't there and he got a different slave - he would probably end up in their village and marrying all them moms anyway, but it never really was out of spite.
Dude basically is a weirdo who likes women disliked/discarded by the rest of the world he is in, so he can basically be just nice to them and swim in pussy. Heck, he didn't even want to retaliate towards the "evil ex-husbands" or the kids, the moms forced his hand, so he gone with a way that will help the ex-husbandos get young meat, but meat that will train them to be better men, just with a side issue of the kids probably not having homes to get back to, which in turn will kinda force them to "learn to grow up". Zeckt is already on his "getting better ark", so are the 3 girls being trained to be good wifes

.
But I agree this is b-class movie level of stupid, to read for stupid plot and use as a fap material if you find them girls/sex scenes usable for that. Not really a place to start endless political or alphabet battles.
Only a good thing, if we will have full sex scenes of side characters. Otherwise it will just piss me off