That was meant to be a friendly warning from someone who I can assure you is very much in the know and very closely placed to this subject both now and in the past.
By your own admission " Captains may be a different case". I assume one day you may grow up and want to become a Captain. In the past commands have been available in Topswizz to UK SFOs being upgraded as dictated by the needs at the time. If this were to happen now ther would by an outcry from the swiss union and swiss FOs all waiting for upgrades.
The link between UKEZY and SWISSEZY is like a drawbridge that the company can pull up and down as and when they please as there is no formal industrial agreements on anything as they are two seperate entities that can help each other out from their own resources when it suits them.
I have actually seen the swiss offers and have read much documentation on them and there is an emphaisis on haveing a desire/interest in working in Switzerland if you choose to go there - I cannot help you read between the lines much more than that if you cannot see it for yourself, all the precedents on this were set long ago.
Bottom line no industrial agreements between topswiss and EZY, means they can do what they like, as long as you understand that, enjoy the move.
PS might want to ask yourself why EZY hasn't mentioned any of this to you but a colleague who "knows nothing" with no invested interest in wether you move to Switzerland or not has. Carry on biting the hand that really feeds you, it will serve you well.