Did I miss something? I don't recall Star telling Tom to wear Marco's clothes, or to eat his favorite foods? Or suggesting it either. Or even depicting her giving him those things.
I think you're confusing subtlety with non-existance. Here's what would've been subtle.
Star writing a list of people to invite to the party and it shows she writes Marco's name first, then Tom's later.
Star glancing at Marco every-so-often. Doesn't have to be center-screen too, could've been in the background.
Star suggesting going on dates with Tom to places that just-so-happen to be where she and Marco went before (and the show not outright saying or mentioning marco for extra subtlety)
Star helping Tom buy clothes and says she likes him in outfits that just-so-happen be reminiscent of Marco.
Star chilling with Tom and seeing a magic car show and she states her favorite in the show is a dragon cycle.
SHIT LIKE THAT is subtle.
Star hasn't done -anything- all season. That's not subtle, that's abrupt character change.