The worst case block validation costs that I know of for a 2.2 GHz CPU for the status quo, SegWit SF, and the Classic 2 MB HF (BIP109) are as follows (estimated):
1 MB (status quo): 2 minutes 30 seconds (19.1 GB hashed)
1 MB + SegWit: 2 minutes 30 seconds (19.1 GB hashed)
2 MB Classic HF: 10 seconds (1.3 GB hashed)
Two things:
1) These are apparently estimations; so this is inadequate data. Blocks differ in size, and types of transactions in them.
2) The comparison makes little sense as they've added a hard limit in Classic.
Your wrong, follow the posts in the thread url. The hard sigop limit is the way to fight such attacks. All times are for worst case blocks than can be used for attacks and the same computer to make the comparsion fair.