Looked at your page, and the sructure looks pretty darned good. One suggestion, get that thing up off the ground onto some concrete pier blocks. I don't see pressure treated ground contact (PTGT) lumber being used for the base, and without that, the life of that shed will be short.
Before he adds the floor, buy three 4x4 PTGT posts the length of your coop. Buy 9-12 pier blocks. Use 3 to 4 per 4x4 post, preferably 4. Jack up one side, place pier blocks and 4x4 under the right wall, set it down. Jack up the other side, set the center pierblocks and 4x4, then set the left side pier blocks and 4x4. Lower into place.
That is the only issue I see. Plenty of ventilation along the eaves.
Tell him this tomorrow, when it isn't your anniversary.
My dad grew up in Rochester and Springfield. I spent many a summer there. You folks do have some humidity. I miss the fireflies and summer evening thunder/lightening storms.