Wherever we see the emperor, we see "ice-cream." There's some obvious difference going on here that's contrasting a stuffy emperor with the fun image of ice cream. Ice cream, perhaps more so than its other sweet counterparts, symbolizes all of those happy moments we may think of when we imagine its deliciousness. More than that, this sensation of happiness is what suspends our cares for how we look, how much money we have, who loves us or doesn't. It distills the essence of life into a single, focused moment. In that way, ice cream represent the true, authentic way to approach life: moment by moment.
Line 3: As a symbol, ice cream can represent the delightfulness of life, lightheartedness, and even sensuality. Those "concupiscent curds" point to the pure enjoyment of life in a sensuous form: food!
Line 8: Notice that "ice-cream" is the very last word in each stanza. We both begin and end the poem with that notion of enjoyment-in-the-moment.
Line 16: And of course, we see it for the last time in the last line. Again, we're leaving the poem with one thing in mind: ice cream and all of the delicious joy it symbolizes. That focus on a pure moment of life, according to the poem, is something we should all strive to embrace.