I searched the original sources of this article and it does not mention anything about Syrian forces being the target of the operation. All of the source material states that Operation Shader is targeting ISIS, not Syria.

I understand the reasonable speculation that Operation Shader could be used to conduct covert operations against Syria, but I think it is important for us to understand that this is speculation and the British did not, as far as I'm aware, admit to actually impersonating ISIS to attack Syria.