Yes. The card is worded very carefully to only have that possible interpretation.
By this you mean because "Attack and Block values" is plural? I see your point, but I think it would have been clearer to write, "Their Attack and Block values of all types..."
This card is insanely awesome, by the way. I just used it with Maximal Effect to get +6 to all Attack and Block values of all my units. Fire Siege Attack 11 on my Catapults took out two city defenders before they could strike, including a White one.