Note the line 'As the temperature of the blackbody increases, the peak wavelength decreases'
Just because some things can be approximated for varying degrees of usefullness as absorbing and emitting equally well on all frequencies (which the earth is really bad at anyway), does not mean they are stable in temperature.
It really doesn't.
This might help. http://astronomy.swin.edu.au/cosmos/B/Blackbody+Radiation
Note the line 'As the temperature of the blackbody increases, the peak wavelength decreases'
Just because some things can be approximated for varying degrees of usefullness as absorbing and emitting equally well on all frequencies (which the earth is really bad at anyway), does not mean they are stable in temperature.