Simple answer Tourchwood- Adult show with sexual themes and Adult behaviour Doctor Who - A family show

If the doctor shows up in Tourchwood loads of children would be watching the show just to see the Doctor simple answer really (that's why he showed up in the Sarah Jane Adventures because it's a kids show)

Xander Kravist

Torchwood: Adult show with sexual themes and Adult behaviour 
Doctor Who: A family show

If the Doctor shows up in Torchwood, loads of children would be watching the show just to see the Doctor (that's why he showed up in the Sarah Jane Adventures because it's a kids show).