Other mistake: When Michael walks into his office and sees Shawn, Michael is wearing a wedding ring. Looks like he forgot to take it off prior to shooting the scene. (01:00:00)
Other mistake: When Michael is looking at the 2009 report about Doug giving his Grandmother flowers, the net total for the action is -4 points. But the totals are off. The positives add up to about 73 points, but just the negatives that we see are 162, making the net total at least -89. While the header implies only the "top" points are known, the numbers start tailing off drastically after the first few, so there's no way there are enough not mentioned to make up the difference, otherwise they'd be classified as "top" too.
Answer: No, he is fictional. The joke is that, despite being handsome and charming, Larry Hemsworth is so overshadowed by his brothers that nobody else has heard of him and he feels like a failure.