Someone told me that the 300c limit was not just due to energy absorption requirement with RTO, but also due to the 400c flash point of Skydrol - therefore you need below 300c to be able to retract the gear after T/O to prevent heat build up in the ldg gear bay and possible hydraulic fluid fire.
EDIT: Not flash point, but autoignition temp.. is this the stuff?
<<- SKYDROL 500B-4 FIRE RESISTANT HYDRAULIC FLUID>>
Fire and Explosion Hazard Information
=======================================================
Flash Point Method: COC
Flash Point: =160.C, 320.F
*****Autoignition Temp: =398.9C****, 750.F
Extinguishing Media: IN CASE OF FIRE, USE WATER SPRAY (FOG), FOAM, DRY
CHEMICAL, OR CARBON DIOXIDE.
Fire Fighting Procedures: FIRE IFGHTERS AND OTHERS EXPOSED TO PRODUCTS OF
COMBUSTION SHOULD WEAR SELF-CONTAINED BREATHING APPARATUS. EQUIPMENT SHOULD
BE THRORUGHLY DECONTAMINATED AFTER USE.
Unusual Fire/Explosion Hazard: PRODUCTS OF COMBUSTION INCLUDE HAZARDOUS CARBON
MONOXIDE, CARBON DIOXIDE AND OXIDES OF PHOSPHORUS.>>