I'm 100% on your side regarding this one.
My first reaction on hearing of plans to demolish the statue was 'Are they raising subscriptions to buy the gelignite? I'll gladly pay for a stick or two.'
The Scots Magazine article has made me think more carefully and your approach is ideal so long as the sod is surrounded by plaques telling what he did.
Nobody else seems to have thought of the workers who built the thing, good on you.
All the best