I don't really see the issue, if you aren't planning on leaving in the next two years then who cares how big the bond is, if you are thinking of going then you have a choice to make. Perhaps that is exactly why the airline is doing it, I know from my current and previous airlines that they all retained the right to bond for change of equipment and or upgrade training and the EBA had a clause like 'the pilot won't unreasonably withhold agreement to any such agreement'. So check you EBA, if you are planning on departing in the next two years then try and go sooner rather than later, if you are planning on staying then don't worry about it.