Boy, consider the situation: tax evasion is a crime, tax avoidance, however, is not only legitimate, but you, your little clown Cadet, and the man on the Clapham omnibus, would claim every possible expense you could to minimize your tax bill IF you could get away with it.
If you, or any other newly qualified frozen ATPL, could set the cost of training, and other expenses, against tax ( tax avoidance) I'm 100% certain that you, and they, would.
If certain pilots, regardless of where they work have discovered, or been led to, a tax solution which legitimately allows them to minimize their tax liability, it does not fall to your knight in shining armour Cadet, still wet behind the ears, to shake the tax man dragon by the tail and point him in the general direction of investigating said loophole.
As the present incumbents of Govt are so fond of telling us "It is within the rules": that being so, Cadet is doing no one any favours by flagging up this up to the taxman, not himself or his colleagues.!
He can carry on shouting his big mouth off until someone discovers he was the culprit who closed the loophole when he suddenly find his working life becomes unpleasant.
Ask yourself how you would feel if someone demanding to exercise their "rights" doubled your tax bill?
And for the avoidance doubt I'm a UK taxpayer.