The Shu”t Shevet HaLevi (9:170) discusses this question and says there is room to be lenient and not to go down due to kavod habriyos [human dignity]. (Especially considering the Gemara in Berachos (55a) which says: Three things shorten the days and years of a person’s life, one who is given a Sefer Torah to read from and he doesn’t, a kois shel berachah to make a berachah with and he doesn’t etc. However, the achronim say, that if there is a reason one refrains then he isn’t included in the curse, therefore, perhaps in our case as well there is a reason the lender is turning down the aliyah, and perhaps it’s ok).
The question is, however, if there is an inyan לצאת ידי שמים , to go above and beyond and to pay the borrower back for buying the aliyah, or do we say it’s a mitzvah therefore there is no need. If the borrower is the gabbah and he allocates the aliyas for free, certainly there is no need to pay back, and on the contrary, paying him would make things worse and it will make the gabbah gain from his misconduct (חוטא נשכר).
(Based on a Teshuvah from R’ Yom Tov Sanger, Madanay Yom Tov Vol. 6, siman 12)
