Programmatically, there would be no reason. However, the reason may be in readability; wrapping an arbitrary piece of code in a transaction is a pretty good way to draw the attention of future developers to it - or from something else. It might also just be that the best practice at the time of writing was to wrap any database transactions in a transaction, just like wrapping stuff in try / catch-blocks.
My suggestion: If because of this, the code becomes more understandable and readable, or if all other database calls are in transactions, leave it. Otherwise, delete it.
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