Your demographic assertions have a couple of PROBLEMS.
1. By your logic the Russians should have recovered from their civil war, the Stalin pogroms and the mass depopulations the Germans imposed in WW II when they murdered millions of young teen aged boys. just a few incidentals.
And they had. The Soviet Union had recovered from the Civil War in 1927, decades beforehand. In economic terms, GDP, GDP-per-capita, and industrial output all returned to pre-WW2 levels by 1948, per Mark Harrison’s works on the subject. Stalin's anti-Jewish pogroms occurred later, nearer his death and don't seem to have reached a scale which hurt economic activity at all. And per Walter Dunn's works on Soviet manpower, the Soviets generally found that the Germans were unsuccessful in denying more then 10% of the occupied regions potential military manpower.
2.
Here. The veterans can be at the front fighting, or they can be trying to put a shattered country back together. They cannot do both and against a West backed by an intact United States, they cannot last. They have no staying power and no reserves. Hence "glass".
Nothing in your link contradicts anything I’ve posted and, as the numbers I have posted show, the recruitment of enough men just to bring the Soviet military back to it's WW2 manpower levels would still leave about 3 million more men in the economy then was the case even
AFTER the 1945-1947 demobilization. Additionally, it ignores that the manpower the Soviets released after the war actually represented the
least capable soldiers available to the Red Army. Per Victor Gobarev's work on the Red Army during the Berlin Blockade, the great bulk of the most experienced, physically fit, and capable Soviet soldiers were retained.
This is in contrast to the American demobilization, which largely let their most capable and most experienced soldiers return to the workforce, with deleterious effects on discipline, training, and overall combat readiness that would dog the Army well into the Korean War.
Additionally, after reaching it's nadir in February 1948 at 2.86 million, the size of the Soviet military began to increase as the Cold War intensified. The Soviet Group of Forces Germany alone received 80,000 additional soldiers in the Spring of 1948. By the time of Stalin's death, it was 5.3 million. According to you, the Soviet manpower situation means this build-up should have been impossible without devastating the Soviet economy. Yet not only did the build-up happen, it happened and the Soviet economy would continue to grow well until the 1970s.
I image more would starve in 1949 to keep the spearheads fed.
The Soviets had already demonstrated their ability to maintain and even increase agricultural production while mobilized, as the increase of agricultural production from it’s low point in 1944 from it's low point in 1943 shows. Additionally, as the political circumstances of the proposed war means it likely won’t last longer then a year, it likely wouldn't last long enough to have much negative impact on Soviet agricultural output. Certainly the taking of Western Europe, which would take a few weeks if it doesn't take a few months, wouldn't last long enough to do it.