It might be better suited there, but it was asked here.
Unless a question is specifically off topic here then there is no reason to push it around the network and potentially alienate users by forcing them to work out where they end up, logging into a new site and so on.
If the user were to flag their question themselves then it would probably be migrated straight away, barring the question being explicitly off topic on the target site.
If you want to give them a gentle nudge then perhaps a comment along the lines of
Hi, this question might get more attention at our sister site Sharepoint. Rather than simply repost there you can flag your question and ask the moderators to move it for you, or you can delete your question here and re-ask it there. If you would rather your question stayed in this community then that's fine too. Welcome to Superuser!
For more information see Migrating questions to the Ubuntu or Linux/Unix Stack Exchange sites