I very much doubt you could be a coward and an activist to the extent that Ewan was in the twenties and thirties and thereafter; McColl joined the Communist Party around 1929 aged 14 and remainded committed to the Socialist cause for the rest of his life.

He obviously had his reasons for opting out of 'joining in' the second world war which came about after the rise of Hitler's fascists during the great depression caused by the failings of the Capitalist systme that Ewan had 'fought' against all his life. To say he was a coward is plain stupid, life aint that simple.