Segwit is technically a hard fork because it changes the security model of bitcoin and makes segwit and non-segwit coins NON-FUNGIBLE due to having different security models.  People who claim it's a soft fork are either full of shit or do not understand anything about the word fungibility.  Or possibly since bitcoin is not even fungible in the first place, they just pretend that screwing up fungibility even further doesn't matter.  But that's not how it works.  If it's not fungible, it's not money in the first place.