Yes, this setup will work.
One thing to keep in mind is that the IR receiver of your DVB dongle will still be setup with the kernel driver's default config (in most cases to decode the manufacturer's remote, eg hauppauge remotes on hauppauge dongles - ir-keytable will tell you which table is active). If that causes issues (eg when you also use such a remote in the same room) you'll still need aluminium tape or blacklist the IR receiver driver module.
The only case when you might want to run "ir-keytable -a ..." manually is when testing a new setup, to check if it works and eg find out if you have typos in your files. This is why I mentioned it in the wiki Infrared Remotes [LibreELEC.wiki]. If you are sure everything's correct you could also just reboot so the config is automatically applied.
so long,
Hias