L = { < M > | M is a turing machine and }
Obviously, the language which L(M) is polynomially reducible to, is context free and hence recursive, so it is a decidable language .
Now, L(M) is reducible to decidable language.
I think this language is not decidable, as this language is non-trivial in the sense of rice theorem, as no recognizable language can be a part of L(M) and even this context free language belongs to L(M).
Is my understanding right ?