Peershares was developed as a platform to create DAOs/DACs. Jordan Lee received funding to build NuBits, but before that could be done, he first needed to build Peershares. Nu was built off of the Peershares platform. It is however not the responsibility of Jordan Lee or his team to keep the Peershares repo up to date. His ultimate goal was to build Nu, not to provide this platform free of charge, therefore all further development by his team has been spent on Nu itself, rather than Peershares.
A new Peershares based DAO is also currently being built by Jordan, which is called B&C Exchange. Rather than pull from the outdated Peershares repo though, they used the NuBits repo, which was more up to date. I'm not sure they will be updating Peershares unless there is a good reason. Good developers are limited in number and they've been put to work on the DAOs we already have and are currently building.
Maybe in the future it can be updated as more developers are attracted to Peershares because of the success of Nu and B&C and other DAOs we build. For now though, the most updated Peershares repo is Nu, except for the fact that it has things built into the protocol which are specific to Nu and wouldn't apply to other DAOs. For example, it has code which Peershares lacks like motion voting, custodial grants to print more shares, but it also has things that don't apply to other DAOs like parking interest rates. You would need to take the extra stuff out that you didn't need.
