It's the "mother" personality doing this. It's contradictory just like how Pudding couldn't decide whether to be a evil or love Sanji.
But according to spoilers, Big Mom destroyed P1 not because of Tama, but rather because of what happened with okobore town with Tsuru and the rest
Look, I am someone who would simply understand if Oda wanted to write it simply as "Big Mom feels indebted" because they took care of her when she lost her memory, simple reason...
But there is no need for Oda to write stuff like:
- Big Mom has a code, and Kaido's crew don't
- Or she's in her Mama mode shitty stuff
Lol
Like, no fucking need to do all that stupid stuff.
Just make it simple, and it will be convincing
In fact, that's what most people theorized when she lost her memory
And Chopper was taking care of her at first, they thought, she will be indebted, thus become an aid in future, not enemy
So no need to overcomplicate a simple thing now by saying she has a code when she betrayed others before, and lied through her teeth to Sanji about letting SHs go or her alliance with Germa lies...
Makes Zero sense to bring the "oh Big Mom has a code, kaido doesn't"