There are differences between, "earn", "xurn", and "deserve". And "get".
If xurs prices were higher Id say it was 100% deserved. Oftentimes though, buying from Xur is more earned and, sometimes, more deserved, than from other sources. See "deserve".
Earning something is like, doing x because you know you'll get y in return. And x must be = y in terms of value.
Deserving is optimal. Examples of deserving are soloing atheon and Crota at the same time. You deserve a hefty reward. But that doesn't mean you'll get it for sure.
Get it is self explanatory I hope.
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Optimally, you'd get what you deserve.
And applying this newfound knowledge, you can deserve GHorn from either performing a great feat in a mission or pvp, etc, or performing a worthy feat in the weekly, then purchasing it from Xur with your coins.
And I'd like to add, practically the only thing you earn in destiny is strange coins.
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So in an applied conclusion, those who Xurned, earned their coins. Those who bought Gjallarhorn with their coins deserved it on varying levels. So DeeJ is right of course.