Numbers: Deleting rows in Sort results in deletion of rows not included in the Sort

Are you sure you mean sort and not filter?

Sorting reorganizes your data based on the conditions you set.

Filtering hides rows that don't meet certain criteria. The rows still exist, they're just hidden.

Consider the following table:

If I Sort this by, say, Quantity, all the rows reorder:

and I can delete any rows I like.

However, if I filter the data, to just show, for example, orders of between 100 and 200 items:

I get a much smaller list. The other values are still there, but hidden. The important part is to note the row numbers - you can see that rows 5, 6, and 7 (amongst others) are hidden. However, if I drag to select rows 4 and 8, I'm inherently selecting the intermediate rows, too. Toggling off the filter shows this:

So deleting the filtered data will also delete the intermediate fields in this case.

The counter to this is to Command-Click the rows you want to delete, rather than drag across them. There's a subtle difference in how it's displayed:

Command-click row 4 and row 8:

vs. click-and-drag across row 4 to row 8:

where one has selected the intermediate rows, and the other has not.

I can't see a case where this could happen via sorting, which is why I think you may be filtering your data instead. If I'm wrong, please let me know.