To find it inappropriate to describe your children in this way?

[Snoopy104]

A friend of mine (well, more of an acquaintance) has 2 young children. Her partner is very active on social media and frequently posts pictures of them, but he always captions them with swear words.
It's seemingly meant in an endearing way, however it just feels uncomfortable. He posted a picture of their 3 year old daughter and wrote 'Happy birthday to this cheeky little bitch!'

And called their son 'A little shitbag'.
Like he uses words like that about his children publicly, nobody seems to comment about it on the posts. It just seems very odd to me, or am I overreacting?

I hate the word bitch, it is by far the biggest insult anyone can direct at me. I never forget when someone has used it against a woman or girl. He sounds seriously messed up and I would be avoiding him like the plague.

SIL constantly refers to nephew as little bstard or little tat

I hate it.

That's gross. There's a woman at the park who calls her toddler "maggot". I think she thinks she's being funny.