Interesting, after re-associating the file with scalc, just to be sure, then checking the key you provided, there was no change in the value:
Is the same before, and after. I’m assuming I should manually edit the value and all would be right with the world?
You could also look for the srt_auto_file in the registry, and try to see what it has. MS changes the way how it registers file associations often; the *_auto_file was a great new thing at some point in the past (and it used HKCU registry hive to override the system-wide associations in HKCR); maybe it’s in use again in, say, Windows 11 (I have 10), or it may be used in some association scenarios / on Thursdays / whatever … 
Yes, and it seems fine.
But what does your commend line inspection shows, using the Task Manager? Is --calc there in the command line when you launch an SRT?
Yes; and it means that either the file cannot be recognized by any Calc filters, or that your installation/profile is corrupt. I’d try to clean the profile first. And provide a sample SRT (rename it to, say, ODT, to please the site engine, that would not allow files having extensions other than an allowed set).
It was definitely the encoding. Wanderer’s solution of Saving As worked. It was encoded as
And thank you for the help
No, it wasn’t “encoding” (any plain text file with any encoding would fit Calc’s Text filter), but rather a file format - it looks like you managed to save it as a Writer file (OpenDocument?) previously, using the old extension (which prevented all Calc filters, of course). The important bit is - what did the Save As dialog suggesting you before you changed that to Text (Encoded) as @Wanderer suggested.
But anyway, nice that you figured it! Thanks @ajlittoz and @Wanderer.
The before encoding was the screenshot here. It was saved as an srt, I saved as a txt with unicode utf-8, then changed the extension to an srt and it opened normally.
Not quite. It’s close, but not a duplicate. The questions are similar, yes, but my question is that I already have set the scalc to open, not the soffice, yet it still opens Writer.