That's the joke, isn't it?
A fission power plant simulator lets you have fun playing through a meltdown disaster scenario. A fusion power plant simulator is "worse" because it takes away the "fun" of meltdowns. The humor is in reacting to the simulator as if it were a game (some are, but this one isn't).
The first line reads as a joke, but then they actually ask if it's safe later in the comment.
I probably could have worded it better but while I understand the process and the inherent safety vs fission, I am no expert in the nuclear field. I suppose what I should have asked is what are the risks of e.g retrofitting a fusion reactor into an existing Con Edison facility in the middle of Manhattn, e.g. the historic IRT Powerhouse on 59th st.