I don't see what the noble will get out of finding out the MC'S skill set.
As explained in this chapter, skills depend on lineage and get inherited. In rare cases this is not so, but could be a "throwback" from 2 or more generations ago. Like how kids don't fit the "family mould" , but maternal gramma remembers the tyke looks and acts like her mother..
Either way, people have a traceable, predictable, lineage on their skills in general, and at least
some existence prior to coming to the attention of nobles. And MC has none of that. He's an enigma.
And contrary to the whole "evil aristocrats" thing peeps seem to fancy here, I rather feel the Aristo's in this case are actually conscientuous in their duties:
You simply do not let enigmas run around freely without keeping a check on them, especially ones that are potentially extremely powerful, and making
absolutely bloody sure they're not a danger to you or the people under your care.
Because proper aristocrats understand the quid-pro-quo of their position, and the responsibility that comes with it.
As for what they could get out of it... MC's production capabilities are well out of the ordinary, and if they could figure out the "why", they could try to duplicate it. Through breeding. Mix and match the right traits.. Get the right couples together, incentives, the works..
Eugenics
works, it works for livestock, in a more haphazard way in Nature. It's just that the downside what to do with the culls is.... unpalatable... to the vast majority of people. Including myself, with emphasis.
If that doesn't work, having a positive relationship with someone proven to be "Mostly Harmless" could well benefit them, in too many ways to count.
They could, of course, incarcerate him and figure things out from there. But that would most likely upset the status quo with the Guilds, and positively would be counterproductive for a working business relationship in the future...