This isn't a hill I'm willing to die on at all, but it does mildly annoy me that The Open Source Definition is used by proponents to mean the same thing as "open-source". For anyone not familiar, The Open Source Definition is a document used to determine whether code should be certified by the Open Source Initiate as "OSI Certified". Proponents argue that anything which does not meet the OSI's definition is not open-source, while I think there's room in the language and the mind for disagreement on whether "open-source" and "eligible for OSI certification" are synonyms.
The OSI was originally founded with the goal of registering a trademark for "Open Source", but this was unsuccessful as the term is too broad and descriptive. Failing that, the OSI decided to instead register the trademark "OSI Certified", which can be applied to works which meet their Open Source Definition. Ultimately, what this means is that nobody owns the phrase "open-source" and it's an organic part of language which is not strictly defined by the specific terms of any certifying documents.
Over the years, there have been plenty of non-commercially licensed software with source available for use: a popular example is video, computer and arcade game emulators. The MAME emulator was for years released under its own non-commercial copyleft license before eventually being relicensed under BSD (which meets OSI's Open Source Definition), and popular SNES and Mega Drive/Genesis emulators Snes9x and Genesis Plus GX both continue to be released under similarly "open but non-commercial" licenses.
I'll happily agree that none of those are eligible to bear the "OSI Certified" trademark and that they don't meet OSI's Open Source Definition. But when people start saying they're "not open-source" it rubs me the wrong way, because we're just talking, not trying to achieve trademark certification. Not to mention that the whole nature of software licensing is to note what restrictions there are on the use of the code, e.g. most open-source, copyleft licenses deny you the right to use their code without attribution. However, we basically all agree that that's fine and you can still call a license open-source if it includes that restriction. It's a shades of gray situation that people are treating as black and white just because a definition exists which they can refer back to, with the assumption that all people must subscribe to those specific terms.
There's entirely valid counter-arguments, of course. It's useful to have strict definitions of nebulous concepts like open-source because it could cause confusion, and you have to draw the line somewhere or else the term becomes completely meaningless. e.g. You risk people referring to things like source code leaks as "open-source". There are frequently cases of people ignoring non-commercial license terms and selling those softwares (Snes9x and Genesis Plus GX are often bundled with commercial retro emulation hardware), which you could argue stems from confusion about whether or not commercial use is allowed. But the same devices often violate the licenses of OSD-compliant software as well, so it seems more likely they just don't care about open-source software licensing terms.
So anyway, Genesis Plus GX is open-source but I'm not willing to fight you about it.
Of course it's subjective. The terminology of the left-right political divide originally referred to 18th-century France. In the 21st century, we're usually not defining the political center of a nation by how it compares to the French Parliament of 250 years ago. The center moves over time and space, and the left and right are relative to that center.
I do think this comment thread is confusing people, though, as noted in an above edit. For clarity, nobody is saying neoliberalism is a center-left movement.