MB, I think more self-righteous pprunere by those denied the medal through the chosen date. If the Arctic Star can be back dated there is only one logical reason the LS can't be - cost.
Not just the cost of the medal but the mass of administration handling the requests. The Veterans' badge was relatively easy - check records, issue badge*, LS would need far more effort.
*I tried to have my
VB 're done with a clutch pin. The jeweller said it was so cheap she could not do it as the badge would melt. Medals are rather more expensive.