I don't think you're quite the target audience for this then.

It's $9... And most apps don't give you access to source. This seems very reasonable.

Would you still pay for it if the source were available? (Fellow indie hacker here)

Not OP, but I would and I have (Blink term emulator for iOS)

I bought it because i couldnt be bothered to set up XCode, figure out the build, and sideload it. Im not a pro-developer so that always takes me time. Also the price was reasonable. In fact, that the source is open encouraged the purchase for many reasons.

I think one of the problems of Stallman and the GPL (I love Stallman, anI think he was the most prescient visionary of the field of computing as it pertains to society) is that there is little recourse for a GPL project to get punked by a freeloading company (who will often not even acknowledge their use of GPL nevermind open source their code). I think Stallman and the GPL are still right, but there are issues that need to be better addressed (i don't know how)

I might not need OP's app but generally for apps I do need, I'm happy to pay some premium for open source for the added trust and risk of being ripping off.

yes. there's a problem with the QC35 I want to fix. It will beep everytime it loses or gains a BT connection. when I'm watching a movie and my phone is in the other room, the headphones constantly connect and disconnect from the phone, making an incessant beeping.

Hacker News is a strange combination of capitalist and libre. The man delivers value. Why should you be entitled to the fruits of his labor for free?

FOSS is a gift. No one is obligated to give a gift.

as others have pointed out, he'll probably make more money giving this away and putting ads on his page.