he literally doesn't want Luke's team to crumble if he revealed that Bruno is working as Derrick's minion. how is that isolating Luke? some of us already misread him coz of the scissor situation previously which the author denied was a tactic of his to keep Luke's attention only on him. he just cares enough for Luke and his passion that he friendzoned himself coz he wasn't sure if Luke thinks they're more than friends but he (Andrew) is not being forceful about anything. he cares enough to make sure Derrick Taylor and his minion don't try to get in Luke's way. it's hardly isolating the person he likes

I am sure, Andrew wouldn't tell Luke whom he saw. He would use this situation to isolate Luke from his "Friends?"
He is kind of going through the motions of seperation anxiety, so Andrew might try to use this panic state to make Luke weary about his surroundings, meanwhile making sure Luke sticks with Andrew.
I guess I am just making up things in my head. (⊙…⊙ )