DH playing mortal f'ing Kombat with DS aged 4.5

[Bizzy2011]

Title says it all, he says its fine as he's explained its not real and he 'covers his eyes' during gory bits.
I'm hopping mad at his attitude, DS informed me that 'its not really mummy and fighting games are'nt very good'. DH all 'research is inconclusive' blagh blagh.
Any advice, links to solid research that if necessary I can shove somewhere painful on DH?

Thanks in advance.

[OohMavis]

So your DH is ok with your son watching shit like this?

It's not real though so it's ok

Warning: Graphic video, even if it is 'pretend'