The push could easily be kept lagged and the damage unlagged, but it would probably defeat the purpose of no lag for HPB. The push could always be remove? Or only for those who prefer to turn no lag on (client side option)?
Either way most HPB ppl already have to live with this and you don't see them complaining. Why? Simply cause it's not that much of a problem, it would rather a problem when you are hit rail gun than ever the mega chain and as I stated before I don't think rail gun should be unlagged if support for this were to be added.
Also if this were to be added it would of cause be a server side option and even if only 5% of the servers were to run this it would make far more people happy than you can imagine.
May I ask why you are REALLY so much against this? Do you fear losing your low ping advance? Trust me it's not the end of the world. Far bigger !HARDCODED! changes have been made to WFA and ppl have and will adjusted and the chances are you will never have to play on unlagged WFA server if you don't want to, if this will be made server optional.