They are certainly 'one piece', but in terms of 'imposing extraordinary costs on Pakistan', their redeployment (or lack of) does not impose significant costs on Pakistan.
The more exorbitant military costs that Pakistan is facing today, and will increasingly face going forward, are those incurred by Air Force and Navy in acquiring newer assets. Take a look at the sticky by Xeric in the land forces section that outlines some of the statistics related to PakMil businesses, budgets and expenses, and you will see that the Army budget is decreasing as a proportion of the total military budget.
Redeployment of heavy artillery is not going to make the Pakistani Military suddenly start trusting India and stop investing in upgrading its capabilities, so even if your argument is that 'India should keep tensions high in order to keep Pakistan investing in its military', the artillery proposal will have no impact on Pakistani policy in that regards - only a resolution of the Kashmir dispute will.