Hi Paul!
Using Clone Stamp for manipulating the image is destroying the data and is therefore not recommended.
Use the data in the image to build a mask.
Using the Script "ColorMask" you can select the Cyan data out of your image
und use the resulting image as a mask to remove the cyan reflection data in your image.
So, put the Cyan Mask over the image,
call MuktiscaleMedianTransform (MMT),
X the longwave layers 4 to 8 !
move triangle over your image and
this removes the cyan longwave layers.
As this would be done over the whole image it is recommended
to do this only on a preview over the specific area und return back the corrected Preview data
with the Script "SubstitutewithPreview into the main image.
You can do this in a second and third step also with Curves and Desaturation.
Never use gimp or other 8-Bit or 16 Bit painting programs as you will loose
all the dynamic in your image.
You dont have to go outside PI and the 32-Bit dynamic room for any solutions even if you want
do steps like Alex recommends... PI offers these not recommended possibilities also but
without loosing data.
Gerald