Ehm that's not saying anything.
I don't know what he's responding to: but all that you an prove, with the combined evidence of mass spec, NMR, IR, etc, is *what* a compound is. So, we know it is this nerve agent with this chemical structure. There is absolutely nothing like a "Russian signature" that could be detected based on the chemical structure itself.
The only worthwhile context he adds is that it is a difficult reaction and wouldn't be possible without a sophisticated lab. But that again means nothing wrt Russia or anyone else, I imagine every country has a chemistry lab good enough for some difficult synthesis.
The evidence implicating Russia remains political, not chemical.
Edit - my credentials aren't like his, but I can say that interpretative spectroscopy was my strongest field within chemistry.