I am very much in favor of this spend. Bringing permissionless validation to an Ethereum L2 is not just big for our DAO, but marks a huge step forward for the industry as a whole. Not surprised to see Arbitrum leading here 
I do have long-term concerns with paying proposers ETH in order to compensate them for their opportunity cost on their bond, however.
I do not want to draw attention away from the fact that I believe this is definitely something the DAO should approve in its current state, so I will link to this concern here for those curious. A working group should likely be formed over the coming months to continue iterating on BoLD’s implementation. This is something I would love to take part in!