User blog comment:B214/Volume 17 spoilers./@comment-117.193.172.96-20140220163805/@comment-1359322-20140221013312

It's just to allow them to enter Issei's house not like some life and death situation where Issei has to choose one and abandon one. (ಠ_ಠ).

In the first place, there was never such a ruling that M&M couldn't enter Issei's house./