Are you implying here that the above statement is a LAW to be ENFORCED by Muslims?
It’s a logical Islamic principle that mosques built by Muslims should be used/looked after by Muslims.
There are two types of Mushriks mentioned in surah 9. Those accused of breaking "oaths" made to the Muslims, "plotting to expel the messenger" etc and those NOT so accused. The ban on Mushriks visiting the sacred mosque after "this year" has NO RELEVENCE to the members of the former group since they would be killed as per 9:5 WHEREVER FOUND including in the vicinity of the sacred mosque if they ventured there for whatever reason save stating their conversion to Islam. It has relevence only to the latter group who are not be killed/converted (for the time being) and are still able to visit the sacred mosque until the end of "this year". The only plausible reason these "nice" Mushriks were to be banned is for THE REASON GIVEN IN 9:28 ie that they were "filth" (najisun). Why were they "filth"? In the absence of any "crime" except "shirk" it can only be plausibly concluded that they were "filth" because they practiced shirk ie because they were MUshriks. If THEY were to be banned from the sacred mosque for that reason and that reason alone it logically follows that the ban stands and that the Saudi authorities are Qur'anically correct in perpetuating it. How you do try and complicate a very simple situation!
9:5 applies only to idolaters with whom the Muslims made agreements. This confines it to time and place. Out of these, only those who were untrustworthy were to be targeted.
The idolaters in 9:28 were obviously not the ones to be targeted, since they were still expected to trade (study 9:28). 9:28 is a blanket prohibition on ALL the idolaters (with whom agreements had been made) approaching the mosque. Similarly, 9:29 is a mandate to fight Judaism and Christianity (and impose jizya). Not all of them fulfilled the requirements of needing to be fought, but they were a part of the “body” of that time. Similarly, not all the idolaters were “unclean” for reasons of 9:7-13, but they were part of the “body”. So just as 9:29 is confined to a situation (9:36), so is 9:28.
In response to your last question, that is what I meant by “concept”.
The idolaters in 9:28 were those of the time, since it says “after this year of THEIRS”. Their year was based on manipulation (9:36-37).