I'm pretty sure it's politics. The reason is a potential draft, but it is also very potential for now and may never happen. So this message signalizes to the older and/or richer population two messages - "you will be protected by the mobilized army in the worst case" and "you personally will be exempt from the need to sit in a freezing trench for multiple years" (which is not true in reality, if the draft will be needed, higher age will be increased to 60 most likely). So the older and conservative population is appeased this way.

CDU are losing popularity if we are to believe press, so that is one of the populist ways to boost some numbers for elections.