That was believeable until the "grammatical mistakes"
As someone who started his foreign language education in Moscow in the 80-es that is the point where I call bull.
We studied 6 hours of English per week in 2nd grade (that equates UK 4th grade), 7 in 3rd and from 4th onwards all subjects except Russian literature in English. Two of my best childhood friends which were attending the French language school were subjected to the same drill. Just in French.
Now the same Saudi sponsors which sponsor ISIS shopping the malware in Moscow and St Petersburgh and supplying broken "North African French" grammar messages is something I find more believable. Bad _WRITTEN_ foreign language in a professional Russian hit written by the Russians - not so much - I have been on the receiving end of their foreign language education for a few years, that is not likely.
By the way, Damascus is in the same TZ as Moscow (GMT+3) and so is Baghdad and Riyadh (+/- different summertime correction). So out of all arguments that is the most laughable one.