You have multiple mongodb employees, some of them extremely experienced, explaining why you should not do this. You should take this advise.
Adding a non-employee voice to the mix:
Your first second and third options for a replicaSet should be 3 data nodes. Only do a PSA as a last resort.
If I came across the monstrosity you propose the first order of business would be tearing it down to a PSA and prioritising making the remaining arbiter a data node.