What does Ezra 4:11 mean?

Rehum the chancellor and Shimshai the scribe wrote a letter against Jerusalem to Artaxerxes the king as follows,

then Rehum the chancellor, Shimshai the scribe, and the rest of their companions, the Dinaites, and the Apharsathchites, the Tarpelites, the Apharsites, the Archevites, the Babylonians, the Shushanchites, the Dehaites, the Elamites,

and the rest of the nations whom the great and noble Osnappar brought over, and set in the city of Samaria, and in the rest of the country beyond the River, and so forth, wrote.

Be it known to the king that the Jews who came up from you have come to us to Jerusalem. They are building the rebellious and bad city, and have finished the walls, and repaired the foundations.

Be it known now to the king that if this city is built and the walls finished, they will not pay tribute, custom, or toll, and in the end it will be hurtful to the kings.

Now because we eat the salt of the palace, and it is not appropriate for us to see the king’s dishonor, therefore we have sent and informed the king,