Snoke mind-probing Rey has Palpatine’s theme playing. Palpatine has a desire for immortality in RotS, and implies he DOES know how to keep himself alive during the opera scene. Kylo Ren asks for Vader’s helmet to show him that power AGAIN. Snoke is very similar to Palpatine and even repeats his lines in TLJ. Even Snoke’s guards have the same color scheme as Palps’ guards.
I’ll grant you that Snoke having Palpatine’s theme feels now better in retrospective (instead of being just an unsubtle remainder of ‘remember! he’s our Emperor stand-in’). But the rest were just similarities to drive home the parallelisms with the OT (almost everything in the ST, from the ships to the armors, is a reimagining or visual callback to familiar elements of the OT). Since Snoke plays the part of Palpatine (at least until he’s killed off), it was expected TLJ would feature familiar OT iconography in the form of red guards and even its own version of the ROTJ creepy advisers.
Unintended, retroactive foreshadowing that Palps’ return pays off and fits in with.