I'd be disappointed at any ATCO who just lets a non-speaking inbound run "just to see what happens" for a massive number of reasons. Whether it's to get a landing clearance onto the R/T (in case of tx failure on the a/c, thus saving a possible go-around followed by non-radio arrival procedure); to alert any vehicles or other a/c around the runway; trying to establish if there's any other problem the crew are dealing with and have just forgotten; just to confirm that there's somebody actually monitoring the arrivals; etc.
Or best case scenario....the runway's clear, the crew have simply forgotten, they land safely...then end up getting dobbed in, potentially into a world of trouble, when their mistake is pointed out on the frequency.
Utterly avoidable.