Lightroom keeps trying to update catalog right after an update

In addition to the other suggestions, you might move or zip-compress the old catalog file. That way, Lightroom won't find it and you should be prompted to select a different/new catalog.

P.S.

An alternate method of starting/opening a LrC catalog. using a KBS of the APT key plus clicking (or double clicking as required) on the LrC startup shortcut icon:

This can be helpful

• As a diagnostic, allows you to select a different catalog should your current one crash right off the start
• As a diagnostic, allows you to get around the wrong catalog opening despite what should have opened.
• As a way to access other catalogs (some of us keep many, old dogs old tricks, will not change) without opening most recent, or going to our file manager to access them.
• As a way to check integrity at catalog startup instead of catalog closure (during backup)

Oh, and do not forget, you could just use your file manager (Windows File Explorer) and locate that catalog, then double click on it to start.

Instead of understanding a few of your statements (I am not sure when "select "always choose this catalog" shows up) I will ask a few questions.

In LrC /Preferences/General/  what do you have in Default Catalog for what catalog to use? Is it perhaps "Load Most Recent"

 or perhaps, Prompt

or a specific catalog

If it is the first one, Most Recent, and your most recent is not that old version, then perhaps you have a corrupt preferences file.