Which can still be built with another Spokesperson. If the Sheriff missed their investigation today. They can use that Spokesperson to feed the information to Mau5trap/ilduce. That'd be the safest way to go about things. If the Sheriff trusts ilduce and Mau5trap. He can just feed information to them in general and not investigate them for the time being.
I don't think he should do the lather, but I already said numerous times, among others saying the same thing that they'd be idiotic to come out and say what they did when they are affiliated with the Mafia at this point and time. The 1ST RD investigation is very critical as usually this round is a crapshoot if he misses, and if he did, he'll have 3 people he can possibly trust now.
Also, what if what I said was true. What if one of them is killed, the other gets converted with the Mafia somehow? Then the Sheriff is in a PM with one, or both, and then one of them is converted to Mafia. The Sheriff is ousted to the Mafia and we lose our Sheriff early on. It's just the safer play to not both investigating them right now, and quite honestly, avoid contact with them directly.
There are 26 other people worth investigating in this game too.