The process of installing SQL Server isn't going away anytime soon, AWS or pre imaged set ups might reduce the need to install for scratch but those options aren't always...

That... that... seems like some very poor wording on the part of that security setting, that really means it's just one step short of completely public.

If you don't want to drop and recreate constraints, load the data into a staging table, then load the data into the main tables in the proper order to prevent...

Hmm.... don't give them access directly the exported file.  Either email the results to them or copy the file over after creating it with a date stamp.

Sounds like you already spelled out the solution 🙂  Use a case statement https://docs.microsoft.com/en-us/sql/t-sql/language-elements/case-transact-sql?view=sql-server-2017

What kind of job is it?