Since they made the announcement this week that only seniors will be allowed on campus for the Fall, there are a couple of factors that play in the picture:
A) MIT will lose out on dormitory revenues and other income sources that they would have had if students were on campus and from a business point of view will need to minimize operating losses;
B) Trump F visa regulation will restrict international students outside the USA from entering and some may take gap year because of being not able to access internet as a result of bad online infrastructure, government restrictions or both;
Bottom line: MIT may offer everyone on the wait list a spot because of the above and the unpredictability of next year since there is no vaccine. At this stage, this is about
stopping the financial hemorhage and the more students, the lower the financial loss for MIT.
MIT would be justified to do this since everyone on the wait list is qualified to attend and this is an extraordinary situation.