In all cases, you can reverse about 1 hour worth of blocks. In practice, when wallets/exchanges/etc pick a minimum number of confirmations, they are really picking a minimum time. So, if bitcoin had double the blockrate, they wouldn't say 'well, we only require 6 blocks, so you only need ~30 minutes of an attack', but rather, 'we require ~1 hour, so you need 12 blocks of confirmation'.
The main purpose of my post is that to actually pull off a successful attack you probably need more than an hour, so the numbers are making it look like it’s cheaper than it would be in practice (ignoring other factors other commenters have shared about acquiring ASICS, data centers, and such).
You can’t 51% attack Bitcoin for $611K, but your site says you can. While the site can’t be perfect, it would be helpful to make it more realistic. If a news site picks this up and doesn’t understand the nuances they’ll accidentally spread FUD and mislead a lot of people.
Difficulty adjusts every 2016 blocks.