No, Shinji not windmilling or kayaking, just increased tempo, six beat kick and shortened stroke length. After his dnf at Rottnest swim when he went hypothermic 8 miles in, someone convinced him he had to change his stroke for rough, cold water. He didn't need to change, only needed to acclimate to colder temps after swimming most open-water in the South Pacific at 85+ degs.
When Shiji and I swam Bridge to Bridge 10k (Golden Gate to Oakland Bay Bridge) 2015/2016, watertemp 58deg and bumpy. Shinji's stroke rate around 75 spm - 6bk, choppy. I was 55-60spm, 2bk (mostly) and we both finished within 10 seconds of each other. Shinji did more acclimation for SF swims than he did for Rottnest, but cold water was still tough for him to manage. I grew up on Pacific Coast have an extra 10lbs of channel insulation, I'm pretty comfy in mid to low 50's water :-) Given more time, acclimation and practice in cold, lumpy open water conditions, Shinji would move closer to his pool stroke/tempo and I believe he already has