Ratna Well, I made some measurements with my MoodleBox, permanently running, in a closed cabinet, without a fan or heatsink (even during these pretty hot summer days). The RPi 4B is indeed a bit warmer than a 3B+, but I've never got any throttling, and the temperature didn't raise above 65Ā°C.
You may notice that the original article (I don't trust second hand reports), even if it uses a punchy and somewhat misleading title, explicitly mentions the use of RPi as a normal PC, using screen connectors to watch videos, etc.
That's absolutely not the same use than a MoodleBox, where the RPi is used as a headless server (so not using at all e.g. any screen).
In a nutshell, in the standard use as a MoodleBox, I am very confident that it does not require any fan or heatsink.