I have to disagree. The Syrian Turkmens I met in Turkey barely spoke their language and were extremely Arabified. Might have only been my selective experience. Nontheless the Turkmen led rebel groups in Syria were still involved in regular infighting and a lot of criminal activities and haven‘t distinguished themselves much from the other groups. This might make me sound like a armchair general, but I‘d hardly call them experienced fighter, if they cannot apply the very basics, like taking cover or trigger discipline. As seen over and over again by videos published by said Turkmen led groups. There is simply absolutely nothing they bring to the field but additional headache.
It seems this news only popped up by Turkish media, the moment it became public that Syrian rebels have been seen in Azerbaijan. If true, it would at least show the YPG/PKK is better disciplined in keeping OPSEC than those rebels. I also don‘t see it as a good justification. Doing the same mistake.