In this case I would refer you to the legal disclaimer at the end of the datasheet, section 11.2 on Product use :
"Bosch Sensortec products are developed for the consumer goods industry. [...] They are not fit for use in life-sustaining or security sensitive systems. Security sensitive systems are those for which a malfunction is expected to lead to bodily harm or significant property damage. [...] The examination of fitness for the intended use is the sole responsibility of the Purchaser."
To summarize, Bosch Sensortec sensors are not designed to be used in safety applications, where sensor failure could cause injury. The specific thermal resistance data for the BMF055 package is unfortunately not available.