Ace felt that he was having a headache after learning their purpose for coming here.
He wasn't exactly sure how the government became interested in what he was doing but he was impressed by their decisive actions of sneaking into his place to conduct their investigation.
Since he was an apprentice of one of the three Grand Arcanists of the country and he was also the Traceless Hands with decent connection with the NMTI, he already thought that he was on the watch list of the government.
However, it doesn't explain how they could easily come up with such a grand accusation. He doesn't have a suspicious background or connections to any underworld organization to point him with such an absurd plan...
'Ugh...'
Well, he may have a suspicious background considering that he was only a sixteen-year-old young man and was already capable of creating groundbreaking technologies.