As we say in the 'rules', AND is not about being against anything.
So you and your horse performing eventing is not against the rules of AND persé.
To check up on one self, if one is truely following AND, the rule in fact is thus:
Stay true to yourself and you stay true to your horse
Stay true to your horse and you are true to AND
If you are absolutely a 100% sure in your heart that the things you do with your horse is in his best intrest, then you stay true to yourself, your horse and ultematly, AND
On a more personal level, do I think it possible that a horse would truly choose a sport?
I can not answer, for I do not
know.
I believe however that horses can choose whatever makes their human happy or what makes human and horse become like one. In spite of themselves even.
In the case of eventing. Let alone the fact that I have absolutely no talent in jumping
My heart would die of fright that my horses would come to harm by falling down or sustain injuries in the long run.
So for me, any sport would be out of the question.
I do not even put my horses on the trailer more than I really need to and 3 hours a drive is the ultimate limit.
My heart rate goes through the roof when my horses play to rough or trip and fall, or have s tiny fever...
I get up at night to check if they are well
I eat every new food myself to see if I get ill etc.
That shows perhaps the limits I go through for the well being of my horses.
And I think... I know... it is more like an overconcerned mother than a barn owner, yes.
Is that a good thing? I do not know. For now at least my horses are not complaining that I am over protecting them
I hope this answer is useful to you?