It's not the first time I heard that Moitessier had "issues"... But he was a hell of a good sailor, we have to give him that...And I bet his telephone pole mast was heavier then the steel mast I'm thinking about
Regarding heavy masts, they're not all bad, the boat will be more tender yes, but have less chance of capsizing due to the mast inertia. The theory is that the wave will have passed under the boat before the boat has a chance to start moving that mast around.
Try standing with a small aluminium pipe pointing it towards the sky, now move it from side to side as fast as you can. Now do the same thing with a heavier steel pipe and you won't be able to move it as fast... It's the same principle on a sailboat.
Most of the BrentSwain36 were oufitted with a steel mast without any issues.