That’s such a stupid statement.

1. You can still use decimals with Fahrenheit
2. Fever is not measured with 2 decimal accuracy. Generally, 38 = mild fever, 39 = high fever, 40 = fucking high fever. Temperature meters still do show in 0.1°C accuracy because why the fuck not
3. Edit: according to wikipedia normal human body temperature is 97.7–99.5 °F or 36.5 - 37.5 °C

Also as someone mentioned below, it has nothing to do with hottest/coldest day recorded (Though that would be even worse)

Several accounts of how he originally defined his scale exist, but the original paper suggests the lower defining point, 0 °F, was established as the freezing temperature of a solution of brine made from a mixture of water, ice, and ammonium chloride (a salt). The other limit established was his best estimate of the average human body temperature, originally set at 90 °F, then 96 °F (about 2.6 °F less than the modern value due to a later redefinition of the scale).