Thanks for the reply @danielo !
Keep in mind that 4 out of the 8 points you cited are actually benefits that are offered as an indirect consequence of the work done in the carrying out of the mandate. In fact, these are under the sub-section of “In addition to the aforementioned services, the ARDC aims to offer the following benefits”. Hence, these are ancillary to the mandate as opposed to the mandate itself (see them as indirect results that would come about naturally by virtue of members being a part of the ARDC & executing the mandate).
I hope this clarifies the first point. In addition, it’s not a question of number (5v3, 4v3 etc.), but rather, what those actionable items actually entail. To my knowledge, and based on this forum post (Plurality Labs: Arbitrum DAO x RnDAO Co.lab), the Co.Lab is wider in scope in that “We’re helping to develop the Arbitrum ecosystem (and advance the governance and operational capabilities of the Arbitrum DAO and all Arbitrum projects) through incubating ventures that build Apps on Arbitrum.”.
As a sidenote, I think you misinterpreted my point re. the collaborative aspect 
I never said that the ARDC cannot collaborate with RnDAO, in fact I actually stated the following: “think the ARDC could actually have a lot of room for collaboration with RnDAO as they can work optimally in a symbiotic manner”
We need to focus more on interoperability between different groups within the DAO, and less on each ring-fencing our knowledge-base (on this, I completely agree)! However, we should also endeavour to not centralise efforts with one provider, and diversify as much as possible in an attempt to attract high quality contributors, service providers, advisory firms so on and so forth. The ARDC is merely the first step in garnering this interest (which it has, as interested applicants are also discussing joint applications with contributors thereby even having contributor + Service Provider applications - this is naturally a great thing to see!).
To sum up, at the end of the day, it’s not my decision whether the ARDC would collaborate the RnDAO Co.Lab, but rather it would be the decision of the DAOAdvocate following conversations with the ArbitrumDAO + ARDC Members. In drafting the proposal, I had personal preferences of my own on what to implement, however, I had to keep in mind that this is not a personal endeavour, but one that has to be executed in light of community feedback as opposed to personal preference. To channel my philosophical side, I am merely the vessel to get this much-needed collective up and running hopefully
I hope the above clarifies your queries sir! Feel free to reach out to me on TG @immutablelawyer if you want to discuss further!