I agree about the lack of support from unions, but then many heli pilots aren't members of one. Not sure if it's chicken or egg though. Certainly BALPA do not have a good track record for helping out. (The senior BALPA rep who recently went on to the payroll of one of the major companies did BALPA's reputation no end of harm).
I can't understand your point about trying to deny a heli job to a pilot with a fixed-wing rating. How would you enforce it? Would you sack the dual-rated pilots already in post? It would surely contravene basic human rights to deny someone a job because he was also qualified to do another. Any employer trying that one would find himself in court quicker than he could say knife! What about the guys legitimately working towards a plank ticket? Sack them for being.... what? Disloyal? If this rule were to be introduced, do you actually think pilots would admit to being dual qualified? You cannot be serious about this.
Until terms and conditions improve, helicopter pilots will remain a transient population. It's called market forces. At the moment heli pilots are not sufficiently remunerated for their qualifications and experience. If rotary employers do not wake up to this fact then soon there will be a shortage of pilots meeting the minimum experience for some jobs; especially our speciality. They can be absolutely NO complaints about pilots moving on as their qualifications allow them to do so.