I personally like kilts and have always been fascinated with specific tartan patterns for each family heritage but, what he's wearing with sandals and a tie dress shirt combo has me scratching my head.
I remember that page you mentioned but can't find it. I did find the page with a chart that explains shirt and tie combos but without images. https://askandyaboutclothes.com/mens-apparel/style-tips/practical-color-help/
You have to scroll down to the bottom for the chart.
I only dislike the black suit with a white shirt and black tie. Looks too much like a funeral director or chauffeur. Now, add a blue, green, lavender or purple shirt with a colorful tie and it suddenly becomes quite the stunning outfit.
To my eye, any of the olive shades look stunning! You mentioned hunter green being too dark an ensemble for summer? Probably so but I live in Georgia so it's often too hot to ever wear a sport coat in summer.
I have two dark brown jackets that I wore tan or medium brown trousers with and always felt weird about wearing brown and brown. I tried olive trousers with one and hunter green with the other and they look fantastic together.
I'm 5'11" so I wear standard ties with a four in hand knot. I can not wear common ties with a full Windsor. The length just isn't there for fabric to tie that knot so I have a few XL ties for the full Windsor. At 6'3" even with XL ties I bet you will be stuck with a four in hand knot.