“Qāma” expresses standing and is conventionally tied to past time, so it is a logical kalimah. The noun “qiyām” expresses the act of standing but does not, by its lexical signification, include a specified tense; it is an ism.
“Qāma”: action with past tense.
“Yaqūmu”: action with a present/future temporal form.
“Qiyām”: the action as a noun without an inherent tense.
A noun can be used in a sentence about yesterday without becoming a tense-bearing kalimah. The distinction concerns the expression's conventional meaning, not every time reference in context.