I'll disagree with that statement.engine component compositions, etc. ~230F is where a lot of engines start risking damage due to warping components.
The engine metals are perfectly safe up to 300-350F+ as long as the engine oil stays below about 250-275F in the sump.
Most air-cooled motorcycle engines operate in the 275-350F cylinder head temp range very frequently.
Liquid-cooled engines need pressurized Coolant/Antifreeze to stay below the boiling point of the coolant, to prevent hot spots from developing. Once any hot spot develops the whole system can spike quite quickly.
I'll disagree with that statement also.165F thermostats were an old hot rodder solution to inadequate cooling systems that couldn't keep up with heat output at full load; the extra overhead between running temp and harmful temps allowed you to run flat out without overheating the engine
A 165F thermostat can not compensate for too small of radiator or too slow (or too fast) of coolant flow or too slow of air flow, be it in a KLR or any hot-rodded engine!