If you try to make the argument to say that this is theft,
you can certainly use the same logic to say the Hive fork is theft.

Comparing the fork that created Hive and HF23 that took Steem & SBD from the above steem blockchain accounts is like comparing apples and oranges. All the steem & SBD owned by the accounts of Justin Sun, Steemit Inc. & the people who supported Justin Sun are left in their respective accounts in the steem blockchain. They, just, did not get the equivalent of Hive & HBD in the newly created Hive blockchain like all the other steem accounts did.