The height difference does not matter much. Spear and arrow don’t care if they have to poke slightly up or down : P
The idea is that horses get startled by the camel’s scent and behaviour. So a general debuff to enemy horses makes sense, no matter what they are attacked by.
I think OP was more concerned about the rigid army composition of always needing camels in some form.
As he followed up, the light cav could use some love and maybe open up an alternative to tech into.