An attack sponsored by the South Korean government sounds unlikely. South Korea isn't exactly a bastion of free speech, but it isn't China, either.
If by "nationalists" you mean the notorious online community known as ilbe, that's definitely possible. They're a weird amalgam of political ideology and lulz, basically the neocon counterpart to /b/.
But it could just as well have been a shady competitor who got pissed off with Telegram for whatever reason. The social networking market in Korea is cutthroat. Almost everyone treats it as a zero-sum game where you have to destroy all the others in order to succeed. Maybe this competitor was planning to launch what it considered a killer feature and Telegram launched it first. Stickers?
The linked post seems to point blame at LINE. Stickers (large animated emoticons) are a major source of revenue for LINE; if Telegram were to offer it for free then it will really hit their bottom line.
If by "nationalists" you mean the notorious online community known as ilbe, that's definitely possible. They're a weird amalgam of political ideology and lulz, basically the neocon counterpart to /b/.
But it could just as well have been a shady competitor who got pissed off with Telegram for whatever reason. The social networking market in Korea is cutthroat. Almost everyone treats it as a zero-sum game where you have to destroy all the others in order to succeed. Maybe this competitor was planning to launch what it considered a killer feature and Telegram launched it first. Stickers?