With past history in mind, what we be in place to stop easyJet from changing their minds as to what they would offer you at the end of 2 years? Since there would be no permanent contract from the outset, what would stop them from offering a NEC Part 2 contract, 25-40% down on current T&Cs? 50% down? Who knows?
It's too big a gamble, and no experienced pilot in a permanent job will hang their ass out in the breeze for 2 years, hoping that what was verbally discussed 2 years before will still apply. And paying for a TR, to put yourself in that position? Not a chance.
That said, it was free to express an interest, and I suspect lots & lots of experienced pilots will express an interest despite all of the above, things can change after all. Just don't expect them to say anything other than "no" if they are offered 2 year contract with a vague promise for the future, plus self sponsor TR. The quality experienced applicants will suddenly vanish if HR try and be too clever and think they know more than they do.