Is this normal in DBT??

I just started DBT a month or two ago. I was doing pretty well for a while, but crashed recently and ended up cutting myself for the first time in a while.

I brought up this to my therapist, and one thing he told me is that my friend who helped me calm down shouldn't have helped me. According to my therapist, he should have stopped talking to me for 24 hours (this person is also my FP and only support system).

My therapist gave me some homework to call the help line they have set up at the practice. I was reading the little business card they gave me, and it says that you're not allowed to contact them for 24 hours after self harming.

I was wondering if this is something other people have come across in DBT? It seems like a huge red flag. Wouldn't right after self harm be a super important time for people to need support so they don't continue??

If I didn't have my friend there, or if he had done what my therapist suggested, I know for sure I would've just cut myself more, or deeper, or possibly even attempted suicide. This method just doesn't seem right to me.

TLDR: Therapist suggests/advocates for no support of any kind after self harming, is this normal or a red flag?