The dev reply is ambiguous and could be interpreted multiple ways. Does it mean that, in this case, the exception is allowed because a PC doesn't have to take the Merit or that it is not allowed because the Merit is required?
It would really help to have a more clear ruling on this issue.
For example - possibilities might be:
- As per the OP, if you take Brawl as a favored ability, you must take the Merit and put a dot in Martial Arts at creation. If Brawl is a caste ability, you must still take the Merit, but do not have to put a dot in Marital Arts, since it is a caste ability. In this case, the "exception" is not allowed.
- As an allowed exception, it is OK to take Brawl as a caste or favored ability without taking the Merit or putting a dot in Martial Arts (if favored). You still gain Martial Arts as a favored/caste ability and if/when you put a dot in it, you must also take the Merit (later).
#1 is a strict reading of the cascade of 3E rules relating to character creation, where brawl invokes martial arts, favored invokes the ability dot at creation and the dot invokes the Merit.
#2 eliminates the initial merit tax for a granted bonus/hybrid ability when all the player really wants is Brawl.
So...1 or 2...or is there a #3?
Another reasonable Storyteller approach might be to completely separate Brawl and Martial Arts and remove the bonus Martial Arts granted when choosing Brawl.
In my game, I have already ruled that #2 makes the most sense for us, since forced merit taxes and the combined Brawl/Martial Arts rules don't make sense. Also, Brawl is an ability in its own right and doesn't logically or mechanically require any Martial Arts skill. So, re: favored/caste bonus ability - yes - and pay on the layaway plan later, if ever.