If you do not know what to post, do not post. You can research more about open source and close source before posting about it. If you know your post will be irrelevant, why posting.
He does have a point; open-source is about the open nature of the code while Free-and-Open-Source Software (FOSS) is closer to what Bitcoin wallets are. First was FOSS, and then companies coined the "Open-Source" term so that "Free" isn't part of the name anymore since they, as companies, are looking to make profit and/or included proprietary stuff..
Since Bitcoin open-source wallets don't have ads, proprietary blobs or some kind of marketing schemes, you can call them FOSS. For example, Ubuntu is Open-Source but it isn't Free since it has proprietary firmware. PureOS and Trisquel instead are FOSS Linux distros since they are purely open-source from end to end.