Is it normal she is hanging with the guy she knows is upto something?

About 2 weeks ago my sister ended the friendship with this guy.
He was shit with communication but also she suspected hes upto something.
He follows girls on insta too.
Anyways they had few dates and my mum and me along with others say to stay clear.
He ended up blocking her and she said to me the friendship was over.
Literally one day later the little pathetic piece of shit unblocks her and starts talking to her again? She says now they're friends...haha
Now they're hanging out again but I feel like shes not telling me something.
I over heard her saying like something about a relationship status on facebook and saying oh well let other guys hit on me then, as his status says single or something.

Wtf they're only friends so why does she care ?
She said to me she is hanging out as she doenst know him too well irl. So is she fuking lying to me?
Her whole life she has told me who I can and cant hang out with and now shes being hypocritical and hanging with someone I say stay away from.
Shes a little retard I will give her a good hiding if shes fooling me.
She knows what men are like 100%
He also has a kid
Hes fuking 23, Like he knocked a chick up hahahha little fat shit and she broke up with him.
Shame I cant wait till he fucks my sister over. She even watches the bachelor and sees that girls on there have had shit luck lmao
She just wants to be normal she dosnt even like him that much, she is trying to just be one of those typical chicks to fit in with the "hetronormative" society.
Good luck to her ^_^