an additional pilot (in this rule called a ‘safety pilot’) is carried in a second control seat of
the aircraft for the purpose of providing assistance to the pilot flying the aircraft;
There are many ways of providing assistance. There is no requirement that the safety pilot take control of the aircraft, particularly not in IMC. There is, further, no requirement for a pilot to have an instrument or IMC rating unless they are pilot-in-command.
Your advice may be prudent, DFC, but I don't think it's backed up by regulation.