The draft design documents state that any WebAssembly code will have an equivalent text representation - so that is almost comparable to human readable source code. It will not be a linear list of instructions like an assembly source code but will be structured as WebAssembly is supposed to have an AST representation. [1]

I cannot see why FSF will have problem with this then, since if you are distributing a .wasm file you can construct an isomorphic text source code representation from it. This is in spirit with the user should get the source code of whatever they are executing. (Though I agree, it would not be equally readable as original C/C++ source code from the .wasm file was compiled, but then something is better than nothing)

[1] https://github.com/WebAssembly/design/blob/master/TextFormat...