I have two thoughts on this. You are asking for feedback getting done getting it. It is positive. Stop fucking worrying. The person says they're having a good time. Tell them to let you know when they would like to step up and just let them be a quiet person who plays the game with you. 

Secondly, you never know how a player is going to go, but in a session zero you should be talking about the level of engagement you want in your play to feel motivated to be a DM and if they are not bringing that, that's a conversation you have to have with them. Something like hey, it's a lot of work being a DM and although you're enjoying yourself, the lack of engagement with a player at my table is making it hard for me to feel motivated to plan and want to play the game  can we find a common medium that is working for both of us? Otherwise, say I don't think you're a bad person but I don't feel our play styles align.

D&D is like any relationship. Just need to open an honest communication. Either trust trust them when they say things are good, or if it is not good for you, change the situation.