Did you read the comments? The dev himself addressed the concerns, to the point where the OP updated his post (emphasis is mine)

Edit to say this blew up. I didn't realise I was kicking as big a hornet's nest and haven't read all the comments yet.

To be clear, what I don't like about this and other provisions in the terms is the language and implications around data use. I've no problem with ads being shown - I want developers to get paid for the work they do and that makes it possible for users to have "free" access to software if they can't afford to purchase.

I also want to add the response from Boost's dev below to make sure it's visible. You'll see that it is boilerplate but required by Google and was present in Boost for reddit. I just hadn't seen it because I purchased it immediately based on a recommendation. It doesn't make me happy about it but does remove some doubts I was having about the direction Boost is heading.