Not 40% of the transactions. Calling " Satoshi "spammed" message in block 1" is stupid. By default Bitcoin Knots allows 42 Bytes OP_RTEURNs and that is fine, a sane default but also gives people the freedom to set whatever they want.

"sane default but also gives people the freedom to set whatever they want" This is good that people can choose, even though it's quite meaningless setting. There's much more interesting things to look at and configure in bitcoin config, so by default it would be best that there's no limit and if somebody wants to setup some filters for some reason and knows what they're doing, they should be free to do it.