Is the UAE a dictatorship? Absolutely - the newspaper is censored, and publicly challenging or speaking ill of the government is a Bad Idea that everyone knows not to do.
Is it the autocratic dystopia that the article makes it out to be? Also no; I didn't have any problems during my time there, nor did any friends that I know of (including three gay friends). The UAE is basically caught between both traditional Muslim and Western democratic influences, and it's not strictly one or the other. As long as you're not challenging the government or doing anything Muslims would consider bad taste (e.g. public PDA), you're generally left alone.
Which meant I was surprised to learn about the jailing on account of a joke about the name "Nahyan", until I saw, "Another joke Dr. Kharrat tweeted urged the Iran-backed Houthi rebels in Yemen to attack Dubai’s Burj Khalifa".
Iran and the UAE _really_ don't like each other, and the UAE maintains a strong security state at least in part because of it. Urging a Houthi attack on the Burj Khalifa would be taken very seriously, and I'd surmise 1) he ended up on a watchlist when he first made it and 2) the UAE is now using him as political pressure on Lebanon.
To be clear, I'm not at all condoning the UAE's actions here as they don't align with my personal values. That said, I'm not surprised: the UAE takes perceived threats to the state very seriously and doesn't claim to allow free speech, so Kharrat was doing a (from an Emirati perspective) Very Bad Thing that most visitors to the UAE aren't likely to.