Can asking for consent on LinkedIn count as express consent?
Publicly asking your followers on any social media at all would only count as consent if you explain who you are, what they are consenting to, and tell them they can unsubscribe at any time.
Does SimplyCast recommend this?
We would avoid gathering consent using this method, as it can be risky, since comments can be deleted and so on.
But I can still do it, right?
Provided you treat it like any other consent form, you would be alright. Remember, burden of proof is on the sender. Should you choose to ask for consent using social media, you will have to be able to prove that you gathered consent this way.