Not absurd if caused by unforeseen circumstances. A similar case would be an outdoor wedding venue with 400 guests and an indoor hall for 300. If it rains, well, 100 guests must either get wet or leave; they could also get in the hall and put the venue in violation of the fire code, something the venue is likely to refuse and would instead declare the event over without reimbursement in case of non-compliance. And sure the 100 guests who would have to stay out wouldn't include the bride, groom and their closest relatives.
Except that the guests have paid big bucks to attend, which is what made the party possible in the first place. And then one of the guests says "hang on a minute, you can't just kick me out" and takes a seat. At which point, instead of discussing a refund or other compensation for the guest's inconvenience, you call in a bunch of strongmen who proceed to punch that guest, slam him to the ground and drag him out by his feet.