It may be because you appear to be targeting a smaller niche than just "doing serious stuff remotely"...
Finding someone with extensive .NET experience, both web and desktop development history and a deep understanding of web security is enough of a challenge in itself. When you add in the GMT+0 work requirement your working pool of remote workers is even smaller still.
Regardless I imagine that for any work with a distributed team the problem of finding highly specialized talent with the willingness to work remote is universal.
Finding someone with extensive .NET experience, both web and desktop development history and a deep understanding of web security is enough of a challenge in itself. When you add in the GMT+0 work requirement your working pool of remote workers is even smaller still.
Regardless I imagine that for any work with a distributed team the problem of finding highly specialized talent with the willingness to work remote is universal.