Never grown this strain so I feel like Honda has much more experience with this plant and as he is so adamant about it and I have nothing to base my decision on I would say listen to him.
However, generally you can have leaf deformities in other strains for a couple of reasons. PH imbalances are most likely the culprit followed closely by overfertilization. Along down the line there is also viruses that can cause problems as well but there is zero evidence of virus and I dont see any sign of fungus either. The leaves are generally healthy and dark, lush green indicating an abundance of Iron, most likely at 5.6 to 5.8 pH. Though some strains exhibit more pink to purple hues in the petiole, 99% of the time I am inclined to believe they have a Magnesium deficiency.
They are definitely NOT lacking calcium. Therefore, I suggest increasing your pH just a tad and/or foliar spraying Magnesium in the form of simple 1tsp epsom salt dissolved in a 1L spray bottle. Use of something like CaliMagic would give you the Mg but further increase your toxicity of C and Fe. If these are true traits of GG, then you would only benefit the plant by balancing nutrient uptake in my opinion.
Also, consider for most plants that if it was an incredibly hot, directly sunny day, I would suggest lowering the EC/PPM/TDS as the plant is going to be focusing on gathering that strong light and storing the sugars in the leaves to send down to the plant at night for growth during the Calvin-Benson cycle. In the three classifications of plants, it is argued where cannabis lies because it exhibits characteristics of both C3 and C4 classes. In laymen's terms, Cannabis can use the CO2 and use light to grow as long as there is a photoperiod -- promoting 24/0 growth.
However, plants that are grown at high light intensities experience phytotoxicity more often than they metabolise all the expensive nutrients you are applying. Why? Because you are taxing it 24 hours a day to do one job; collect light and turn it into sugars. If you were to lower the intensity of the light periodically, you could feed a higher EC/PPM/TDS to promote uptake during fertigation days as long as you turned your ballast down to the lowest setting for a few hours or place a semi-opaque piece of plastic between the light fixture and crop to simulate cloudy day albedo and intensity loss. That's why growers that use 1000w or better per small plant space experience "extra" growth at night when "things go right."
On top of that, the Low and Slow growth method yields the best results. Lower Light Intensity and Lower Temperatures for Slower growth but stronger and better. Less pest pressure, less respiration/transpiration to control.
Add more beneficials. Myco, Bacillus, Trico, etc.
*I have grown White Widow in Deep Water Culture that took up 4200ppm of Dutch Masters Gold series on a single 400watt HPS. I have also grown Ebb and Flow tables where I had excellent yields with only 900ppm of Certified Organic products under effectively 6- 1000w lights. You really should learn how to determine pound or gram weight of the nutrients in your fertilizers so you can pinpoint any deficiencies or lockouts, and learn the tendencies of the strain to determine what concentration it needs during various stages of growth... That only comes with time, my friend!
Summary:
Increase pH a little to take up some Magnesium or apply it via Foliar application of epsom salt.
Lower Light intensity on feeding days and periodically to encourage nutrient uptake, and attempt to lower temperatures reasonably. If you're comfortable, they are comfortable.
Add beneficials.
Stay high.