Never use a flat paint in a bathroom, period. Even if you add a
fungicide, it will just not be durable enough or water resistant enough
for that use. I agree with the other guy that you should smooth out
the wall if appearance is an issue for you.

I am a big fan of high-gloss paint, appearance aside. It dries hard,
fast, and is super durable and waterproof. I even prefer an oil-based
paint where wetness is expected. I know latex is what everone uses but
if you try the oil based finish you will be surprised at the difference
in the finish compared to any latex.

Just think about it, an oil has got to be more resistant to moisture
and abrasion than a latex. I even used and oil based high-gloss in a
shower stall with excellent results!!! Use semi-gloss where appearance
is an issue, but never use flat latex in a bathroom unless you don't
mind doing it over in a year or two.