We can now understand why Rashi chooses to say, “strangers shall enter this service of {the Levites},” instead of using the wording of the earlier verse, “a stranger who approaches shall die.” This is because these two verses are discussing two different things:
The first verse is discussing the individual punishment of an individual stranger who has committed the sin of “approaching this service of {the Levites}” — the service stated in this verse — the dismantling and assembling of the Tabernacle.
Therefore, the verse says “and a stranger” in the singular, because even an individual is forbidden from taking part in the service of dismantling and assembling the Tabernacle.
In contrast, “this service” that Rashi says here (on the verse, “and there shall be no wrath”) refers to the “service” discussed in this verse, “The Children of Israel shall encamp, every man at his camp... The Levites shall encamp around the Tabernacle of the Testimony.” Here, we are referring to the command to prevent the breakdown of the boundaries (in general), keeping the “camp” of the Israelites and the “camp” of the Levites separate and independent.
This is why Rashi says, “that strangers shall enter,” in the plural. When an (individual) Jew pitches his tent in the Levites’ camp, this does not establish an Israelite “camp” within the Levite camp. A camp can only be formed by many (“strangers”).
Accordingly, Rashi replaces (the wording of the verse, “approaches”) with “enter,” because the word “approach” doesn’t fit in a verse that discusses an encampment in the Levite camp. Instead, the proper word is “enter” (the camp). On the other hand, in the earlier verse, which discusses the dismantling and assembling of the Tabernacle, the right fit is indeed the word “approach.”
