Ofcom was created by the UK government for the sole purpose of enforcing laws passed by the UK government [and sometimes interpreting those laws]. It acts on behalf of the State at all times, and is not empowered to do otherwise under any circumstances EVER.
You appear to be confused about what being a "quango" actually means in this case. "Quasi-NGO" means that while it appears to be a non-governmental organisation, it is not one. Ofcom's at arm's length because the majority of its daily legal obligations are closer to judicial than administrative, and it is UK custom (rightly) to not put judicial functions inside government departments.