I'd argue that in those conditions, that's a less than 50% kick. Generally speaking, for your average NFL kicker in normal conditions is roughly 60%. The extra 15 yards makes it a roughly 90% opportunity... so it takes Pitt's win probability from a coin flip to almost a sure thing. So, IMO, that's a pretty big deal.
To the second bolded, I completely agree. I blame the refs more than I blame either team, honestly.
Well, I didn't say it wasn't a big deal. I was merely pointing out that there is a likelihood that the Bengals lose, even without the second Unsportsmanlike Conduct penalty. To hear Bengals fans tell it, it was either the penalty is called and Pittsburgh wins, or the penalty is not called and Cincy wins.
Edit: The numbers do not bear out your prediction of less than 50%. According to this link, and my admittedly possibly faulty math; NFL kickers were successful on 75 out of 101 attempts from 50+ yards, this season.
NFL Stats: by Player Category
I didn't triple check my math, but I'm confident that I am not off by over 25.
Second Edit: *growl* the default came up to the 2008 season, not 2015. Let me check the numbers for 2015.
In 2015, NFL kickers made 148 of 274 attempts from 50+, for a 54% success rate. So Pittsburgh still would have had a better than average chance of winning the game, even if Porter had been flagged.