Stallman doesn't like it, but RMS is renowned for the scope and breadth of things he doesn't like.
To say that something "viral" can "infect" something else is the natural extension of the metaphor. I can see not liking it, but it doesn't scan to me as unserious or in bad faith to say this.
Edit: this kind of language goes both ways between copyleft and permissive camps in FOSS circles. I see objections to permissive licenses phrased in terms such as "improvements to MIT code can become locked away inside proprietary software", which only works if you consider proprietary software to be a prison, when this is in fact an intended outcome of permissive licensing.
https://en.wikipedia.org/wiki/Viral_license
Stallman doesn't like it, but RMS is renowned for the scope and breadth of things he doesn't like.
To say that something "viral" can "infect" something else is the natural extension of the metaphor. I can see not liking it, but it doesn't scan to me as unserious or in bad faith to say this.
Edit: this kind of language goes both ways between copyleft and permissive camps in FOSS circles. I see objections to permissive licenses phrased in terms such as "improvements to MIT code can become locked away inside proprietary software", which only works if you consider proprietary software to be a prison, when this is in fact an intended outcome of permissive licensing.