Deadlock after setting Single user mode

Question

We have some scripts that are executed during the installation of our application.

One of them is used for setting Database Collation, the other one is used for setting compatibility level. We use the following construction for these scripts:

ALTER DATABASE [DB_NAME] SET SINGLE_USER WITH ROLLBACK IMMEDIATE
GO

ALTER DATABASE [DB_NAME] SET COMPATIBILITY_LEVEL = DB_COMPATIBILITY_LEVEL
-- ALTER DATABASE [DB_NAME] COLLATE 'Collation Name'
GO

ALTER DATABASE [DB_NAME] SET MULTI_USER
GO

The question is:

Is it possible for some background process to get an access after setting single user mode? In this case our script couldn't be executed. I saw this issue and it seems similar, so I decided to ask a question.

https://social.msdn.microsoft.com/Forums/sqlserver/en-US/950c9b85-67f9-4272-8dff-14aa3590bc8a/single-user-mode-session-lost-after-backgound-processes-jump-in?forum=sqldatabaseengine

This issue was related to restoring database.

alter database [test-db] set single_user with rollback immediate;   --This sql is run using test-db
use master;restore database [test-db] from database_snapshot = 'snapshot_test-db';
alter database [test-db] set multi_user;

But I don't fully understand the difference between restoring and altering the database in the single user mode.

In the first case will be enough to set the database offline.

Any help will be appreciated.

Thanks in advance.