The question is, are you tight on the time needed to get the update done every 2 seconds, the “Hard” requirement or not, and if the display update takes like 1 second to process, is it better to have tighter control of the display, but only 1 second of sensor data every 2 seconds, or do you want the full 2 seconds of sensor data?
Presumably, the sensor has some time limit in it that if you don’t process the data from it within some time limit, the data will get lost (because the buffer is full), so the sensor DOES have its own “Hard” time limit, but perhaps you can afford to lose some data. If this time is longer than the processing time for the display, then maybe you don’t even need an RTOS (or you can use one but don’t need to worry about the requirements as much). If you can’t wait that long, then you need to weight the lose of sensor data to what ever “Risk” it imposes on your one “Hard” Specification.