Toys R Us have thankfully confirmed to Joystiq that the Lucario cancellation emails were part of a technical error that plagued the company’s system. So there you have it. If you pre-ordered Lucario with Toys R Us your pre-order should be absolutely fine.
“We apologize for any inconvenience that may have been caused pertaining to customers’ amiibo pre-orders. Please know that we are working on an email communication to all customers effected, which will provide instructions on how we plan to fulfill their order.”
Thanks to those who sent this in.