Because you are missing the other files Microsoft.HEIFImageExtension_8wekyb3d8bbwe Microsoft.MPEG2VideoExtension_8wekyb3d8bbwe Microsoft.VP9VideoExtensions_8wekyb3d8bbwe Microsoft.WebMediaExtensions_8wekyb3d8bbwe Microsoft.WebpImageExtension_8wekyb3d8bbwe
Yes, even removing System Apps many files are kept in the \Windows\WinSxS folder to maintain compatibility with Windows Update. In fact, in WinSxS folder there are hard links to the Windows files and without removing them you have no space gain. So in this case the main advantage is not having these Apps running in the background. I am currently using LTSB 2016 (version 1607) and doing some tests with LTSC 2019 (version 1809) both with 10 years of support from their release dates Well then if you are familiar with PowerShell you will have no problems. In fact the author turned the script into a PowerShell module and divided its various parts into small other modules. Maybe I'm just not using the right tool to edit them.
Be careful with doing that. I tried disabling that service because I have another firewall I prefer and my VPN wouldn't start until I turned it back on.