'Clear' appears as an option on dead trees of other varieties.
When those not experienced with wood trees see
a) a teeny little stump that barely looks like a tree, and
b) the option 'Harvest and clear',
they could be forgiven for thinking the poor wood tree's already dead - especially if the water and pet options are greyed out.
By changing the option to 'Harvest and kill', you'll make everyone a little bit more aware of the consequences of their actions when dealing with these atypical trees.