Are you not being offered the option of training for your talent mark at all? Or is he just reminding you you can't take part in foal-only quests and activities (like the sled race at the Winter Games) once you graduate? (Looks like you got all the foal quests, btw - Knead for Speed isn't one and technically Cloud Race isn't either, though it and Cutting it Close feel like they're for foals.)
I have done eleven foal-only quests thus far including two not mentioned on the wiki page linked below (Cloud Race and Knead For Speed, not sure if foal-only) and Windhover is still trying to convince me not to grow up because I may miss something. Is this just bad dialogue or am I missing a quest? Quests I completed, listed in the same order as they are in my journal.
A Treat For Taffy
Justice's Blind Eye
Can You Hear Me Now?
Foal Speed Ahead
Knead For Speed
Welcome To Equestria
An Equestrian Werepony In The Evershade
A Wolf In Horse Clothing
As per the wiki, linked below, I have done all of the foal-only quests, and the wiki doesn't mention "Cloud Race" or "Knead For Speed", though I am not sure if they are foal-only. Have I missed something or is Windhover's dialogue just incomplete or something? The unicorn and earth pony instructors never made me feel like I was forgetting something.
OK, I found an easier way. I was doing a lot of custom stuff and it had crisp results in the end but it was a lot of work. If you add LoE as a non-steam game to your library and you use Steam Remote Play on your phone, simply turn off the filter on SRP on your phone for "SRP optimized games" and you can play any game in your library, including LoE. If you do this you need a Bluetooth keyboard paired to your Android device for obvious reasons. You can use touch or a Bluetooth mouse for mouse input. Heck, you can use screen mirroring to mirror the phone/tablet onto a big-screen TV and play LoE on your living room TV while doing this!
I thought I would share that I managed to get LoE working on my Galaxy Note 20 Ultra 5G just now. I will post some screenshots later, after I work on it some more. Now I can play LoE wherever, without hauling around a tower containing many heavy parts! Has anybody else tried this yet?
Here we go. I took two quick screenshots. They are slightly blurry, but it works!