It would be interesting to know the truth of this.
My 2.2D, 64 plate, 30K miles, just had a bottom end seizure, I'm not sure what exactly. Always serviced by Mazda, fortunately, so it was covered under warranty. Phew!
To cut a long story short, the tech partially stripped the engine and found what appears to be evidence of a lack of lube, including the camshaft which runs directly in the aluminium head (no bearing shells), so it was a complete new engine - after I had "a bit of a discussion" with the dealer! There was no obvious reason for the lube failure - at least that's what they say...
The knackered engine is going back to Mazda UK next week, presumably for a post mortem. I would love to get my spanners on it to find out exactly what the problem was ! I doubt I will ever find out.