Maybe he meant Afghanistan + Balochistan?
I figured as much, just felt the need to be a little facetious.
Anyhow, the problem with a Turkestan-Afghan-Baloch railway (Turkafba for brevity) would would be required to service such a port would be that it would have to cover an immense distance. Ignoring the usual distance of everything past the Urals to the European Russian metropole, the mountain range that runs through the centre of Afghanistan would probably be too difficult (and expensive) to blast through with 19th century technology. So the railway would have to go around the range, increasing distance considerably, whilst being under threat from local bandits. The Turkafba solution to the 'warm-water port' problem doesn't seem to be the wisest economically. Not to mention the risk from the British. The risk is disproportionate to the reward, so I don't see a rational Russian state doing this, especially given that they have other better options. Even if they implemented this Turkafba idea, it wouldn't have any return.
Let's consider all the directions the Russians can effectively expand:
-East Asia (Manchuria/Korea)
-The Transcarpathian/Balkan region
-Persia/Indian Ocean
The Indian Ocean route appears tempting because it's the only one that reaches an 'open sea'. However, the infrastructure difficulties are too much. Whilst Persia becomes a significant prize, especially when oil is struck, there is a lot of risk of conflict with the British and (more importantly) the population might be a bit too big for Russia to bite off.
East Asia seems to be the path of least resistance, but also becomes an issue once the Anglo-Japanese alliance is signed, as the two powers work in tandem to contain Russia. Nevertheless, Manchuria is very valuable, as is Korea, although East Asians will swamp the Russians in the Far East demographically. However I don't consider this to be a 'dealbreaker' for the Russian Empire. The bigger difficulty here is that East Asia is oriented in the direction of the minority of Russia's trade in this period.
IMHO the Balkan direction was the most rational for Russia to expand. Some of the locals there were more welcoming to Russian presence than the Persians or Chinese/Koreans were, their primary rivals were on the decline (Austria-Hungary and the Ottoman Empire), and a port on the Mediterranean would allow barely-restricted trade with the rest of the world, and (in peacetime) beyond due to the presence of Suez. There was obviously a lot of symbolic importance in Constantinople/Tsargrad, but IMHO the desire for Russia to conquer it was primarily motivated by geopolitical considerations, as it would allow the Russians to 'break out' of the Black Sea into the Mediterranean, increasing Russia's power projection significantly, whilst making the Black Sea an uncontested Russian lake, unlike during the Crimean War.