The original manuscript is not extant here, but in the printer’s manuscript Oliver Cowdery initially wrote they people, a scribal slip. He corrected this to the people by crossing out the y of they. The crossout of the y is in heavier ink flow, which argues that the correction was made later. In other words, Oliver did not correct the they to the immediately after writing they. But since he did write the word people at the same time he wrote the they (both are written inline), the original manuscript probably had the word people. One could argue that 𝓞 read they but that as Oliver was copying from 𝓞 into 𝓟 he suddenly decided to correct the they to the people since they could have been misinterpreted as referring to the serpents. But the use of heavier ink flow for the correction argues otherwise. The critical text will assume that 𝓞 read the people.
Oliver Cowdery’s initial they in place of the was probably the result of the two preceding occurrences of they in the verse (“that they should pursue them no more but that they should hedge up the way”). There are eight other instances in the manuscripts where Oliver made the same scribal slip, writing they instead of the; in each instance, there is at least one nearby instance of they that could have served as the source for the slip:
Thus here in Ether 9:33 the initial they people is very likely a scribal slip.
Summary: Maintain in Ether 9:33 the corrected reading in 𝓟, “that the people could not pass”; here Oliver Cowdery seems to have accidentally written they people initially in 𝓟 but corrected it only later.