I may be over-thinking this due to the choice of words used in "Terror" and "Used to elephants".
p38. Terror. "In addition mounted troops are not allowed to charge elephants. Cavalry that pass their terror test..." The first sentence clearly includes camels but does the second ?
p38. "Used to elephants". There is one mention of cavalry and no mention of camels or mounted troops.
There are a number of rules, charging for instance, which specifically refer to cavalry and camelry together but these two rules on p38 do not refer to them together.
I am also not aware of any camelry which currently have the "used to elephants " rule but this could be an oversight. I am vaguely aware of some Northern Indian armies using elephants and camels in their baggage trains - not much of a precedent I'll admit.