The same is true for BIP110 so by your own logic that would be a hard fork too.
(Of course neither are hard forks; both are soft forks.)
its not, bip110 blocks remain compatible with exisiting nodes on the network which is why there exist the possibility of wipeout (however small). the wipeout risk wouldnt be solved without a solution like your checkpoint, which is a forced upgrade.
ursf to bip110 isnt a softfork
ursf to bip110 isnt a softfork