I am sure as you get older you will understand.
Let me put it even more simply for you.
"Holding pool," simply means thank you for the attending the interview and if a suitable vacancy occurs in the near future we will re-consider your application. It doesn't mean you are next. There is no contract in existence, and if you wish to find employment elsewhere that is fine. Nobody cares what it costs you (except you of course,) to keep your licence current.
This scheme (MPL) is a structured scheme that in order to be successful does require some significant degree of commitment on the part of the participating airline. Common sense should be telling you that these MPL pilots are most definetaly going to be a priority project. They will have been trained with a partial loan from the employing airline that is only recovered from the proceeds of that employment. These MPL pilots will have been trained in accordance with the specific requirements of the participant airline.
These are pilots being fast tracked into a career with the MPL participating airline. They are not going to wait for any of your "hold pools" to empty, or economies to improve. These pilots are not being "sneaked in", they are being fast tracked. Your problem is believing that a reserve pool of possible candidates has any other meaning than "maybe". Nobody, but nobody cares who might or might not be "chuffed". This is all about business, and in this case a new business opportunity. Whether it is successful at the end of the day remains to be seen. However MPL or 250 hour candidate means little in meaningful flying experience terms. The tailored aspects of the training though, will have a particular appeal to the participating airline.
I don't think you had any problem understanding my 4 simple replies to your own 4 bullet points. I think your problem was the common one of not wanting to understand them. No doubt borne out of reaction to your usual reading matter, software licensing agreements?