That transaction would not have been exposed to legal or public scrutiny. Harrison was able to represent it publicaly as not only a donation, but as just 1/6th of its value.
However, the whole scenario of a Mafia Don (even a former one) investing in a high profile corporation in such a high profile way just doesn't happen except in fiction.
"Generosity. That was my first mistake." "Experience must be our only guide; reason may mislead us." "Instagram is Twitter for people who can't read."