MovieMe's answer is correct, but there is another big aspect to it as well. Basically the entirety of Tenet's plan is about making Sator believe that he's won. The idea is that if Sator didn't get the last piece of the algorithm then he'd continue trying to get it, and since he has basically infinite resources being sent to him from the future it's likely that he'd succeed.
Sator's convoluted plan is to put all the pieces together and then bury them under a nuclear bomb. His death will trigger a message to the future, recording the location of the buried algorithm, so that the people in the future can dig it up and activate it, thus ending the world for everyone in the present. In his last moments Sator believes he's been successful, but in fact he hasn't, because the algorithm is pulled out from under the bomb at the last moment. As a result, Sator dies without being able to change the outcome, and his plan can't continue.
So the Tenet plan is to let Sator almost succeed but then thwart him in the last moments of the final battle. This might seem like a risky plan, but it's not, because it's a temporal pincer movement. The whole thing is set up by a future version of the protagonist, who has lived through it once and knows exactly how it will play out. Priya is acting, under his orders, to make sure things happen they way they always did: the protagonist must fail to capture the last component of the algorithm, and the soldiers must fail to defuse the bomb, in order for the splinter unit to be successful in capturing the algorithm in the end.