"Open source" was designed for the sole purpose of being "clever" wordplay and an effective marketing strategy, so you really can't blame fsf on that one.

Words matter. See "pro life" vs "pro choice", see "terrorist" vs "criminal" see "migrant" vs "alleged refuge", etc. etc.

The tech press are mouthpieces for the big corporations, and all of the big corporations do not want free software messing with their profits, so they use and coin words which align with their interests. It's perfectly natural for fsf to use different words.