This is the most likely explanation given Japan’s history of xenophobia and that Nissan is a very high profile, iconic Japanese company
But that's completely orthogonal as to whether Ghosn is guilty of anything. You don't get a free pass for fraud (embezzlement in this case) just because the context is political. I'm surprised that a lot of people are mixing these two things together. There is what Ghosn did, or is accused of doing (embezzlement), and there is why anyone went in to check (prevent the Renault Nissan merger).
The US government is also well known to use its judicial branch to exert political pressure on foreign actors (see the Alstom buyout by GE). That doesn't make the fraud perpetrated by individuals somehow acceptable. But it can justify governments getting involved to prevent these individual actions having larger consequences.