Earlier quoted context omitted.
I honestly don’t care if it is or not, but this has been discussed to death with regard to unreal and the consensus has been (from epic) to consistently refer to the source as “available on GitHub” not as “open source”, because that gives people an incorrect impression of the permissiveness of the license. Is this a hill you really want to die on? It doesn’t matter at all. The “can see code” = “must be open source” a…
"because that gives people an incorrect impression of the permissiveness of the license" How does it? "Source available is unambiguous" It's not, because it could be hidden behind a pay wall.
But you may call source-available software whatever you want, just not open source unless it's under and OSI-approved license.
You can use any words other than the phrase "open source" to be as unambiguous as you want.