I think, they’re saying that they have to use a certain video chat client for their job, and that video chat client doesn’t support screen sharing on Wayland yet, even if Wayland itself would be ready for it.

“Not positive” in this context means “unsure” (i.e., the above commenter is unsure about whether or not OBS works in Wayland, but they rely on some other software which they know is incompatible with Wayland)