Okay so, from what i remember this was my process
Tell him to not tell his fans about his goal
Say yes to the karaoke stream
Once our boy gets sad over the comments apologize for raiding him (Not sure if this step actually matters but just in case yk)
Next time he calls you tell him 'publicity will be publicity' (This'll prompt him to not stream that day since you've convinced him that not interacting with the trolls would let the problem blow over)
It should segway into the ending by then, sorry if it doesn't but from what i've seen and done only two options really change anything about the story so you should be okay