Knots is a fork of Core. It has everything Core has. Not more or less susceptible to Sybil attack as Core
Discussion
I think you misunderstood what the post was about, that is not what I'm saying
Core is very susceptible to Sybil attacks. Check out eclipse attacks. Asmap feature was added to try and mitigate, but it's not perfect.
I'm not sure you know what a Sybil attack is
The number of Core nodes has not increased recently, hence there is no pro-Core Sybil attack