First thing, it depends if WSUS Offline uses Dism or wusa to integrate the updates ... so :
- if it's dism : it may work
- if it's windows udaptes (wusa) : it will not integrate your updates
==> I'm not able to answer you about how WSUS Offline because it seems to use a script, and it hides how the integration is made.
Second thing, WinSxS cleanup is intend to be used if you integrate your updates before installation otherwise there will be possible errors
I wish you to have a nice day !