I don’t see why the malls would have any right to discriminate. Anyone who can afford rent can have space.
Mall owners are free to rent to whatever tenants they choose, so long as they don’t violate any laws in the process. If they want to limit mall tenants to retail establishments, they are free to. If they want to further limit the mall to only shoe stores, they are free to do that. If they feel your particular shoe store would bring undesirables into the mall, they are free to refuse you.
In the case of chapels, I can imagine mall owners refusing chapels because 1) they want only retail establishments, 2) they are ok with non-retail (e.g. a library branch) but the habits or demeanor of chapel visitors could negatively affect sales at the retail stores, 3) they’ve already got one chapel, and more than one could tip the balance too far away from retail, 4) some shoppers may assume the mall is owned by, or shows favoritism toward, a religious group which they oppose. I could probably come up with two or three more plausible reasons, but I think these are all defensible under the law.
The one case where they could run into legal problems would be if they allowed a religious group, but then refused a different religious group when the first moved out, or if they refused a second religious group an even more remote or unobtrusive storefront than a first group that was still renting, in a struggling somewhat empty mall. These actions might suggest that they were refusing not on broader principles, but on the basis of the particular religion itself. I believe that would be illegal, but even then most situations are murky enough that a clever owner could come up with a plausible excuse which was legit.
I also don’t understand the opposite extreme taken by
CathCentrist. Does he propose forbidding mall owners from renting storefronts as chapels, or is it simply his personal preference (“If I owned a mall…”)? He is not at all clear, except to allow Christians should be able to if Muslims have done so, etc.