My understanding of code-golf in general is that you're to provide the shortest solution in a given language. However, for most challenges, you could safely pick a language no one really is familiar with, and write a fairly lengthy code solution without worrying that someone will top it. For example, most of the questions here do not have a solution written in, say, x86 or MIPS. It'd be possible to write a poorly optimized (in terms of bytes) solution in these respective 'languages' (technically assemblies, but whatever), with little worry of it being beaten.
Is this considered ethical?
I suppose the counterargument could be made that making these obscure languages commonplace would both raise awareness of them, and could also create competition, but at the same time, doing so with really lengthy programs seems to fly in the face of the very concept of golfing.