First, in your sentence, the word “unnecessarily” is not only unnecessary, but also a poor choice of words. Think about what you are attempting to communicate with that sentence. You are saying “[there is] no reason to . . . suppress a writer’s creativity by prohibiting split infinitives.” Adding the word “unnecessary” here is not necessary at all, for doing so merely creates a tautology: of course you would think the prohibition on split infinitives is “unnecessary” if you believe there is “no reason” to forbid them.

Second, if the word were indeed “necessary to the sentence’s meaning,” it could easily be moved to follow the word “creativity.” And if you think fixing a grammatical error in this fashion makes you sound like a clown, I should probably clarify for you that the “clown standard” is an objective one, not subjective. A true clown, after all, will fail to understand the problem with split infinitives in the first place, so he will be doubly perplexed if he attempts to revise his sentences in such a manner as to avoid revealing his prosaic handicap.