Well he gets younger with every census
..
In the 1881 census, Michael is aged 10 (correct for Aug 1870 birth date)
In the 1891 census, Michael is aged 19
In the 1901 census, Michael is aged 27
In the 1911 census, Michael is aged 33
In the 1921 census, Michael is aged 42
Well, if you have him in the 1921 census, he didn't die in 1918.
I dont know where you got that information from, but it does not look correct.
You can get his death cert. from Scotlands People.