Former Twitter CEO Jack Dorsey, who now heads the Bitcoin-focused financial services firm Block, is going straight to the top in his quest for answers on why Apple, the giant computer and smartphone maker, doesn’t offer bitcoin (BTC) support for its mobile payment service, Apple Pay.

On Tuesday, after Apple signaled to the Bitcoin-friendly social media app Damus that it would likely be kicked out of the App Store for violating the platform’s terms of service, Dorsey tweeted at Apple CEO Tim Cook: “Why doesn’t Apple Pay support bitcoin @tim_cook?”

He quoted a tweet from Damus that appears to show an App Store reviewer recommending Apple Pay as one way to resolve the violations.

Damus founder William Casarin told CoinDesk on Monday that the tech giant has threatened to remove Damus by Tuesday for violating the company’s in-app purchase guidelines by allowing tips or “zaps” on content paid for with bitcoin instead of using Apple Pay, which doesn’t support crypto.

The spat has renewed questions of whether Apple has too much power over consumer applications, and in some ways validated cryptocurrency advocates’ push for a financial system that’s resistant to censorship.

Cook, who tweets roughly a few times a week, has not responded to Dorsey’s question.

Incorporating bitcoin into Apple Pay – which has over 500 million users by some estimates – would result in a significant boost in mass adoption for the cryptocurrency.

Damus is a decentralized social media platform that runs on the Nostr protocol, which is popular with bitcoiners partly because most implementations of it support payments over the blockchain’s Lightning Network. (Nostr is an acronym for “notes and other stuff transmitted by relays.”)

The app went live in the App Store earlier this year, only to be threatened with delisting on June 13 because of “zaps” – a special Damus feature that allows users to send small amounts of bitcoin (BTC) over the Lightning Network to tip their favorite content creators, much like Twitter’s “tip” feature. Lightning is Bitcoin’s second layer payment network for cheaper and faster transactions.

“Two weeks ago, we identified a feature in the Damus app that allowed users to send a tip in connection with digital content in the app, which violates App Store Review Guidelines 3.1.1 and 3.2.1 (vii),” Apple told CoinDesk.

Casarin said that Apple wanted the zap button removed from all “notes” or content sections – a configuration Apple deems tantamount to selling digital content according to Casarin – although it was fine to have a zap button on user profiles.

“​​I had a call with Apple and they told me that they don’t want zaps to be used for selling,” Casarin explained. “I thought one of the compromises we can do is we’ll actually remove all note zapping functionality.”

He said he modified the Damus interface such that zap buttons would still appear on notes, but the zaps themselves wouldn’t be associated with any notes and would only be sent and processed at the profile level. Casarin says Apple wasn’t satisfied with his compromise.

“I spent the last two weeks removing the ability for users to see zaps,” Casarin said. “I resubmitted it and they just gave the exact same response.”

Apple confirmed it had engaged Casarin and clearly explained to him how to resolve the issue.

“As we previously communicated to this developer, they were to address the issues we outlined to them by their next update,” Apple explained. “Upon receipt of their latest submission, we found the issues were unresolved and rejected their app.”

None other than former Twitter CEO Jack Dorsey appeared to criticize Apple’s decision, arguing that “tips aren’t unlocking content.” Earlier this month, he had tweeted that a move by the tech giant to cut off Damus could restrict Bitcoin adoption and thwart the “one opportunity to build a truly global payment protocol for the Internet.”

Dorsey, who is now CEO of Bitcoin-focused financial services company Block (SQ), has donated millions towards the protocol’s development.

It’s unclear if the looming removal is simply a misunderstanding by Apple or part of a broader crackdown to restrict certain types of bitcoin-focused apps. On June 14, the company rejected an updated version of the non-custodial Lightning-enabled bitcoin wallet Zeus, but it was subsequently approved the next day.

“We review all apps against the same set of guidelines that are intended to protect customers and provide a fair and level playing field to developers,” Apple said.

Casarin and others have criticized the company’s approval process, calling it “opaque.”

“The frustrating thing is that whenever you get feedback from Apple reviewers, they don’t tell you specifically how you’re breaking the guidelines,” Casarin said. “It’s very frustrating. I think a lot of Bitcoin apps are at risk.”