Charlotte has a spotlight on her for You Tied Up My Heart even though she's not singing. Bill has a spotlight on him for Not Your Seed even though he's not singing. they're being pulled into the show, forced to contend with their infected loved ones on Pokey's terms before being properly assimilated. they've already become part of the show before they're part of the hive.
for Inevitable, Emma doesn't have a spotlight on her until the end. because until the end, the point is that Emma's alone now. only Paul gets a spotlight, it's Paul's song, Paul is the focus, Paul is being celebrated. Emma's fear, her attempts to escape, don't matter, she doesn't need to be lit. Paul's corpse basks in the light, flaunting how separated they are now, while Emma runs and screams in the shadows. Emma's not part of the show, Paul is.
only when it's time for Emma to be front and center does she get her spotlight - only when it's fully sunk in for her that she has no escape. that's when she becomes part of the show. the light is on her until she's carried offstage, and she can kick and scream and beg all she wants. the light will still shine on her.