Whole network must upgrade. So spammer spend $1200 but bitcoin network 10x more on upgrade,
You must have quoted my post before I updated it with the new table to estimate the cost to the network that you were referring. I think "10x more" is an overstatement. It still looks like it costs the spammer more than the network as a whole [blue column] if we write the spam to the blockchain, even though I think the relevant cost is the cost per node:
Spammer only spends money 1x during lifetime, but miner has to keep bigger disk-space forever (2 hard disc consume more electricity than single one)
So what, without a cap miner will get paid to do it. And profit and get stronger which is the last thing the spammer wants especially since he can no longer disrupt the user growth which will, in the meantime, lead to squaring of the networks value (price) according to Metcalfe Law.