Would you criticize the IDF cook by saying: “Why are you sitting comfortably in a safe room while other soldiers are risking their lives on the battlefield? Why aren’t you out there in danger, fighting alongside them?”
Such an argument would be absurd. While combat may seem more heroic and demanding than working in the kitchen, if the cooks were to abandon their post and join the battle, the soldiers would starve!
The soldiers and the cooks are partners, each fulfilling a critical role in the war effort.
The same applies to Torah learners and physical fighters:
The ruchniyus aspect of the war is waged by those learning Torah in yeshiva, while the physical war is fought by the soldiers on the battlefield.
The Gemara says (Sanhedrin 49a):
אילמלא דוד לא עשה יואב מלחמה ואילמלא יואב לא עסק דוד בתורה
Were it not for David [who engaged in Torah study], Joab would not have been able to wage war. And were it not for Joab [who fought the battles], David would not have been able to study Torah.
If either side abandoned their responsibilities due to a desire to do the other’s role, it would endanger us all, ch”v.