Not everyone agrees with this definition. If the source is open to read, for me it's open source. The website you linked is an opinionated view on what open source is.
I mean, there's not a lot we can do to stop you using the phrase in this way. But you should know that you will cause confusion. The phrase "open source" is, to an awful lot of people, a technical term with a specific meaning and has been so for decades now.
Not everyone agrees with the OSI definition but I'd say almost noone agrees with that definition there.
I think most people understand what you are describing as "Source Available". Could even be a commercial project.