q is a state variable that defines the two states s0 and s1. Acceptance conditions are defined on states, right. But in symbolic descriptions, we do not work with explicit states like s0 and s1, and rather use formulas on the state variables as replacement of sets of states. So, it is fine to have acceptance conditions on the state variables. Note also that for the first automaton p is a state formula while p is an input for the second one.