I have to say, that although I am not against wannabes opting to buy their own type ratings (a position I predict I will be in) the EasyJet scheme looks very dodgy indeed. However, I don't think one would be bonded as you would simply owe the money back if you choose to leave. What concerns me is why one would owe back so much (est £25k inc interest?) and what happens if they decide to get rid of you?
If you are sacked or made redundant and they stand the cost in such circumstances then maybe, just maybe the extra expense is worthwhile for some. If you still owe them the remainder then this is simply a financing scheme.