Is my brain just making things up?Probably.
(1) Nowhere in the rulebook states that Matilda is slow.
(2) Matilda is elite because its center oval is filled in.
2.4 Elite Units wrote:
some Allied tank units (center symbol filled-in) are elite(3) The subject tanks for the "Allied I-Tanks" optional rule are 1AT and 34AT but not Matilda. You may find a detailed discussion here: https://boardgamegeek.com/thread/124104/optional-rule-allied.... (no official verdict, though)