Such "a"?
No, because 'competition' is an abstract noun (I think)
I would personally have written "benefits the consumer"(base)
It's a common phrase in politics. The truthfulness of the statement is another matter, however :)
How could possibly the competition not be beneficial for the consumer?
"Such competition" feels a little awkward in American English, but the owl didn't like "Competition like that", which feels a bit more natural.
Competition like that is accepted and has been for the last three years.
I don't know why mine was rejected, then.