New form of 51% attack via lightning's revocation system possible?

In a discussion about the security of the Lightning network, René Pickhardt argues that the network is vulnerable to a new kind of 51% attack which allows an attacker to steal up to 99% of all the bitcoins allocated in the sum of all payment channels the attacker was connected to. In his hypothetical scenario, an attacker with 51% of hashing power opens multiple payment channels and keeps track of her (revocable) commitment transactions in which the balance is mostly on the attacker's side. Once she knows enough of these old commitment transactions, the attack executes as follows: secretly mining blocks for 72 blocks, spending all the fraudulent commitment transactions in the first block, spending own funds on decentralized exchanges for any other cryptocurrency and broadcasting the secretly minded blockchain once the attacker has mined enough blocks that the commitment transactions cannot be revoked. The attacker could steal way more BTC than double spending their own funds. Although Pickhardt admits that a 51% attack becomes less and less likely with the growth of the Bitcoin network, he does not see any reasonable way of preventing this form of a 51% attack. To prevent such an attack, Pickhardt suggests that no one should have more than two or three times the amount of BTC they own in all the payment channels they have open.