I did some investigating,I found no connection between Leonard and Jose. Lana has said there is no relation. It's a fairly common Spanish sirname. Perhaps the spelling is preventing your recognition - phonetically it is Padiyah. There is at least one professional baseball player with that last name(Vicente) as well as a popular DJ whose name is also Jose Padilla.
The only connections I can see is Tim McVeigh's recognition of the name because his best friends ex-wife married a guy in Las Vegas named Leonard Padilla in 1990. This may have partly led to this supposed friendship with Jose Padilla, when they both resided in the same part of Florida in 1993-1994. Other factors such as their disdain for the government, interest in guns, etc. may have also fostered the supposed friendship.