Peter Todd takes over the MARA channel that carried more than 9,000 BTC past the public mempool

Only MARA's miners can confirm a transaction sent through Slipstream. The service routes it to MARA Pool alone ^[2], and Todd, quoted by Bitcoin Magazine, said it promises to keep transactions "secret until they're already in a block" ^[9]. No other pool sees the transaction, so none can compete for its fee. Cryptopolitan's report does not include Slipstream's fee schedule, its transaction count or MARA Pool's share of hashrate.

Bitcoin's relay policy is separate from its consensus rules ^[5]. According to the Bitcoin Core documentation, relay policy is a set of additional, locally configurable rules that nodes impose on unconfirmed transactions before accepting them into their mempools ^[5]. Once a transaction is in a block, those rules no longer apply ^[5]. A transaction can therefore be valid and still fail to reach a miner. StarkWare's quantum-safe test sat in that gap until Slipstream carried it ^[12].

Todd has now built both kinds of route around default policy. Libre Relay loosens the rules for any node operator who chooses to run it ^[6]. Slipstream grants the exception inside one pool, and the fee stays with that pool ^[2].

Coldcard added a second use, secrecy, to the original one of getting large or non-standard transactions mined ^[4][7]. Slipstream had been running for about 29 months when the advisory came out ^[1]. "If you've already reused addresses, this isn't relevant, and you should just try to move your funds ASAP. But if you haven't, MARA may be able to help," Todd said, according to Bitcoin Magazine ^[10]. On X he wrote that "it's really interesting how Slipstream was useful during the coldcard hack" ^[13].

The channel could go several ways from here. It could stay an emergency and testing route, used when a wallet flaw or an unusual script makes public broadcast risky or impossible, with fee income too small to matter to MARA. Pools could instead compete for private flow, with fees on sensitive and non-standard transactions going to whoever pairs hashrate with a maintainer users trust. Or Bitcoin Core's default relay rules could move toward what Libre Relay already allows ^[6], leaving private routing mostly for secrecy cases like Coldcard's.

I think the first fits the record best. Cryptopolitan's report says private mempools are gaining ground and that fee revenue and miner control over blockspace are becoming more central to how Bitcoin is secured ^[14]. The documented cases behind that claim are one wallet rescue and one experimental transaction ^[11][12]. The strongest counter-case is the size of the rescue: a channel that moved more than 9,000 BTC in a single incident ^[11] has shown real demand whenever public broadcast is dangerous. If MARA publishes volume data showing steady Slipstream traffic outside emergencies, my view is wrong.