...Matthew 12:30 is for that who actively oppose or reject Jesus Himself.
In essence, one says those that are not actively agianst Me are still against Me. And the other says those that are not actively against you are for you.
To paraphrase further. It’s as though one says that if you are not actively against me, you are for me, and the other says if you are not actively for me, you are against me. i.e. one tells the guys in the middle they are against Him and the other tells them they are with Him.
You have to read the context of the Luke passage. There were people out there doing things in Jesus’ name and actually promoting Jesus. The Disciplines got miffed and asked Jesus what to do about them and he gave his answer. Matthew 12 is teaching something entirely different.