I don’t think that’s bad, it means that all of his data is very high quality. If you don’t meet his requirements (eg don’t have a release in hand?) that’s up to him.
Feel free to add the information to MB though, although we do ask that you provide sources we don’t require anything for you to start editing.
You also don’t have to ask anison.info for permission to use them as a source for MB - data like tracklists and catalogue numbers etc don’t ‘belong’ to a site like that.
So basically… go for it!
You can then use tags or collections to keep track of your additions/anime songs.
One thing you could do is ask MB to add anison.info to the whitelist for relationships to other database, so we can link our releases to theirs, but I’m not sure if that’s what you’re after.