While expectations may differ, I'd consider this as a bug:
Some text aligned at a right tabulator (e.g. in a header line) wraps to the next
line (left aligned) if the text's left margin exceeds the position of the centre
tabulator. While at first this may seem plausible, I'd consider that
inconsistent, because the text at the first (left) tabu­lator would have to wrap
for the same reason at the position of the centre tabulator.
I could also agree with the wrapping if there is actually text at the centre
tabulator, but a tabulator by itself is a non-printing character. So as nothing
happens if left-aligned text crosses a tabulator position, there should happen
nothing if a right-aligned text crosses a tabulator position (from the right).
However currently it causes a line break, just as is the tabulator stops would
define table columns.