If, for the sake of argument, there were 20,000 Core30 nodes and 1,000,000 Knots nodes, then the spam would make its way through the Core30 nodes and would be mined.
Therefore, your goal isn't really to have more Knots nodes; your real goal is to decrease the number of permissive - i.e. Core30 nodes
nostr:nprofile1qqs8fl79rnpsz5x00xmvkvtd8g2u7ve2k2dr3lkfadyy4v24r4k3s4spz9mhxue69uhkummnw3ezuamfdejj7qg4waehxw309aex2mrp0yhxgctdw4eju6t09uqsuamnwvaz7tmwdaejumr0dshsu0ur8h has some good YouTube videos on this.
TLDR- more knots nodes means it takes longer to propagate blocks containing spam, while a competing block that does not contain spam will be accepted by the network much quicker. So miners adding spam to their blocks run a higher risk of their block getting orphaned and that risk goes up with knots adoption.
