The bug
Since pufferfish don't poison creative mode players, Wither roses shouldn't wither creative mode players either.
Linked issues
relates to 4
MC-266319
Wither roses effect players in creative mode again
Open
MC-138675
Wither skulls inflict the Wither effect on players in Creative mode
Resolved
MC-141107
When the player kills the patrol leader in the creative mode, it will give Bad Omen effect
Resolved
MC-205069
Powdered snow doesn't give you frozen effect in creative mode
Resolved
I dont see how this is a problem really.. doesnt do any harm to leave it and it even might be useful for something else down the road..