gold is GPL v3. Even if that route was less work, it wouldn't be compatible with the LLVM project's goal to produce a permissive-licensed suite of tools (UIUC, broadly similar to BSD).
This matters to important LLVM backers like Apple, who employ a lot of the core devs.
"LLVM project's goal to produce a permissive-licensed suite of tools"
This is really far down the goal list ;-)
"This matters to important LLVM backers like Apple, who employ a lot of the core devs."
As mentioned numerous times, the vast majority of core devs are non-Apple at this point.
More to the point here, the person who wrote the blog post, and is responsible for the vast majority of LLD as it exists today, ruiu, works at Google (happily, ELF is being pushed along by others as well)
I'm responsible for the entire C++ platform there, and I can happily state that i don't give a single whit about whether LLD is permissively licensed or not.
This matters to important LLVM backers like Apple, who employ a lot of the core devs.