hello folks! hope all is well! i am desperate need help or any advice about my husband problem in work now.

just recently he has a trouble with hes manager even though he done nothing wrong with his job at night shift.
all the blame from the mistakes of a colleagues the manager put on blame to my husband or in our understanding it seems like a blockmail just to suck him in job in a small mistake! hes been 16 years already in that firm in a night shift job, its a pain all of a sudden he got a letter from the manager saying that they offered a "Life Line" and they want them to transfer my husband in a day time and under observation for 12 months!
were been already in a citizens advice beareu but looks like no help from them!
my questions is: is that in justice that they offered a life line with under observation of 12 months?
they dont even give a consideration for 16 years working in that firm... my husband a little bit worried if he will transfer in a day time and the manager will find another mistake or blockmail again just to suck him in that firm.

how can we do about this problem? where do we find help about it? by the way that firm is no union thats why my husband he dont know what the best option. thank you in advice