It is clearly very unethical if you did either of these actions with any amount of chips if you have an edge of 20% and sold at a premium.
QFT, and for future reference on a staking thread coming soon.....
I think there are probably a few other issues with staking and re-entry tournaments. Some people who are 1.2 at the start is unlikely to be still worth 1.2 if they re-enter in level 8 for instance. Though this can depend where there strengths lie. I am probably at my strongest early on, where as others have great stealing/restealing games when the antes come in.
But back to the question.
Say somebody sold at 1.2 in a £1k tournament with 25k chips and their EV was £1.2K in this tournment.
Assuming I didn't realise I was just buying variance, and I had bought 50% of the action at 1.2.
At the end of day 1a, my horse is sat there with 5k chips. As a staker, I may still think I have roughly £120 worth of value in the tournament (5k/25k x1.2). My horse has 50% of himself too, and has £120 worth of value.
But my horse can re-enter tomorrow selling 50% of action at 1.2. If he is a genuine 1.2 chance, he can buy in tomorrow for £1K again (he pays £400 and I pay £600). As a backer, my £600 is worth £600 tomorrow, so buying in for 1B is +£0 before variance for the backer. In isolation, buying in to 1B is worth £200 of EV to my horse (his £400 gets him £600 of EV).
So if my horse threw his 5k chips away at the end of day 1a, he would be £80 better off in EV terms (£200-£120).
If I only backed him for the first bullet, I lose £120 worth of EV. If I back him at 1.2 for the second one, I still lose £120 worth of EV. It is only if I back him at 1.0 for the second bullet that I do not lose out by his decision to throw away his 5k in chips.
In fact, ignoring tournament variance, our horse can happily throw his chips away and gain right up until he has 8333 chips.
It isn't just re-entry tournaments with this option that have this issue. A horse that can sell at a premium has a financial incentive to throw away chips in any re-entry tournament when he gets short. Because of this, his 10 BB shove range should probably be much larger late in the day from any position.
You can probably throw in the natural inclination for most poker players to dislike playing a short stack. Most poker player's are going to be happier going for the win with a big stack, rather than grinding a short stack in to day 2.
I play a lot of rebuys and if you can rebuy on 2k chips, and double rebuy on 0, and I find myself sat on 2500 coming up to the end of the rebuy period, I try and engineer situations that mean I can get down to 2k or up to 4k. This is partly because I believe that my move in isolation is -EV, my extra chips are +EV, but there is also a part of this due to the fact I simply prefer playing with 4k chips rather than 2.5k.
I played day 1 of a re-entry on a french site the day before yesterday, and my stack was quite a bit below starting for a significant period. Throughout most of that period I was sat there thinking if I don't get motoring soon, I can just re-enter tomorrow. This is pretty much the same thinking I have in rebuys.
So if I can start thinking like this where my financial incentive to do this stuff really isn't that high, then I think it is safe to assume a lot of horses will be thinking the same way even before you bung a financial incentive for them to act in their own self interest on top.
These things together make it a pretty unpleasant state of affairs for a backer. This is why I tend to baulk when I see staking proposals for re-entry tournaments. This is particularly the case where there is no mention of what levels the horse will re-enter, or even if they are planning to re-enter.