The function stake in StRSR.sol is used by users to stake a RSR amount on the corresponding RToken to earn yield and over-collateralize the system. If the contract is in paused or frozen status, some of the main functions payoutRewards, unstake, withdraw and seizeRSR cant be used. The stake function will keep operating but will skip to payoutRewards, this is problematic considering if the status is paused or frozen and a user stakes without knowing that. He wont be able to unstake or call any of the core functions, the only option he has is to wait for the status to be unpaused or unfrozen.
Consider if a contract is in paused or frozen status to turn off all of the core functions including staking as well.
