Earlier quoted context omitted.
> > fellas > Not just men! Men, Women, and everything in between. fella (fel·la) - nonstandard spelling of fellow, used in representing speech in various dialects. So we follow 'fellow': fellow (fel·low) - a person in the same position, involved in the same activity, or otherwise associated with another. And so we can conclude that this is completely fine . It can easily be reasoned that the GP was using it to refer…
https://www.merriam-webster.com/dictionary/fella https://en.oxforddictionaries.com/definition/fella Nearly every usage of "fella" I've heard has had a "male" implication. At least in US English.
Neat, and I've heard it implied multiple times to refer to generic groups of people, in US English as well too just like you. The thing though we need to consider is definitions, facts, sentence context, and even the auhtor's intent much more heavily then both of our personal experiences.
It can easily be argued based on context that the author's intent was to refer to a group of people generically, they even used the "nonstandard" and generic version of the word.
Personal anecdotes do not make facts.