Contrary to your comments on your change of a couple hours ago, "stoic" is not and never has been a verb. It is both a noun and an adjective. "Stoical" does exist, but it is an uncommon variant on the adjective usage of "stoic", which is in general the preferred form. References: Cambridge Dictionaries Online, Merriam-Webster's Learner's Dictionary.
I reverted your change because your "correction" adds no benefit to the article, and because most readers would actually see it as some kind of error, given how infrequently "stoical" is used. I'm a professional writer with a degree in English from an Ivy League university, and I had to double-check that "stoical" was a real word.