In my opinion this "protect me on a later flight proactively" is a North American thing which I rarely hear form European airlines but I might be wrong. My guess is that the agent did not protect you on a later flight but tried to rebook you and screwed up. What I did not understand when the OP became aware of the unusual rerouting via MAN? At the airport at YOW during check-in, during transfer at YYZ or even earlier? Who did the rebooking? An agent at the airport at YOW or YYZ or was at someone at the LH backoffice? If it was done at the backoffice when was the OP notified? I also do not understand the luggage situation. Why does the OP think the luggage would be routed via MUC instead of taking the same route as the OP. Sorry for all the questions but with the limited information at hand we can only widely speculate.