Scarfs and clothing in general are thought of as warmth-bringing but they only reflect our own heat back at us - they're insulating. In Frosty's case the scarf would insulate him from rising external temperatures and keep him cold longer.
A scarf doesn't create heat. It only holds it in. So, this comic is even more disturbing than it seems, because Frosty must have an internal source of heat that's slowly, inevitably melting him away.... It's just occurred to me that this is analogous to the human aging process.
Recently, I saw a toddler ask her mom why a snowman decoration was wearing a scarf. And the mom decided to go the playful route and said that the snowman is probably cold. So, the toddler followed up asking why the snowman is out here and not inside the house, where it's warm? To which the mom replied that it would melt, if it was inside...well, uh, not this one, as it's a decoration made out of wood.
And like, yeah, these are some tough questions.
Do you just explain to a toddler that humans put up decorations, which don't always make infinite sense?