Belgium had a similiar policy and we see how that worked out. Swiss can afford such a policy because of its geography.
Certainly, Switzerland is more defensible than Belgium, but I have not found any references to indicate that Belgium required all of its citizens to keep military weapons at home, or that it had a policy of immediate activation of the entire male populace if invaded.
Do you know what percentage of the population kept weapons at home in Belgium? If it was similar to the Swiss, It would be most interesting.
The Belgians were not armed.