This is a relevant point, but 1: that's not their objections 2: it will have to be done sooner or later. If the cost is fixed, do it sooner and rack up more savings during 'later'.

Now, if you can show me that migrating to wind or solar or nuclear will be much much easier, cheaper, simpler and more efficient if we do it 10 years from now instead of next year, then it might be a good idea to wait.