I made two tiers of a cake a couple days ago and covered with ganache for the first time.  I did a royal icing drip on it and because I’m in such a humid environment, it finally hardened after two days!  I had planned on freezing until the birthday which is in one week.  At this point could I just leave at room temp???  I have a lot of other sculpting to do and since the royal icing is taking so long to dry I definitely need to do it soon!

if it was me -- I'd fridge it well sealed in a box and plastic wrapped, or sealed in a plastic bag -- or both --

if we could turn back time, I would ganache and add the drip a couple days prior to serving -- I would have kept the cake frozen until then --

the ganache might lose it's pretty finish thawing out -- might not but that's why I would hesitate to freeze it -- if you do decide to freeze -- thaw it in the fridge slowly for a day or two -- 

best to you

to answer your question, nine days is too long to keep a cake at room temp without losing quality -- would most likely still be edible though -- you just risk tasty freshness --