I am not really sure how this is even good for those that PVP? Its limited that means even if you are dedicated to PVP and played it all the time before that you might still be out of luck of ever getting this..They could make it a PVP wolf marks reward and set the number of marks you need quite high. So it would be reachable for everyone that wants its but still would need work to get it.

Would people be okay if in savage the mount or the gear would be restricted to the first 100 people that beat it (or first 50 people)?

Well who knows maybe the reskin of this will land in the cash shop...because they know a lot of people will want it and most of the players wont get it..with that they create want and bamm its in cash shop in another color somewhere down the line..sorry my cynic side talking.