A horse can only be claimed by the person riding it, regardless of how rude killing wild horses and horse theft can be. That being said there is never a scenario where it is acceptable to intentionally hit a teammate. I'd also like to say that talking in chat about how you're going to get someone banned and/or [X] is a retard/bundle of sticks/etc and will get banned instead isn't the best thing for admins to see when investigating a case.
Prayamantus, since this is your 3rd ban for team killing/wounding and the second such ban issued against you in the last week I'm setting the duration at 24*(2/3) hours.
Edit: Also refrain from spam posts in ban threads in the future.