meaning - Is "has made it his business to" polite or impolite?

In this sentence:

He has made it his business to reintroduce the theory to a new
generation of activists.

1. Is "has made it his business to" an impolite expression?




2. Is it a radical expression?




3. Has it any implicit meaning that he reintroduces the theory, but he shouldn't do it?

EDIT: These answers confused me, First sentence of Source article may help better understanding this expression in the context.

Answer

To make [a task] one's business is to devote oneself to the task, and treat it as a priority. There is often an implication that the person is taking on a task that no one else is willing or able to do:

When I saw what state the club's books were in, I made it my business to ensure that all of the accounts balanced correctly.

Depending on the context, this may be a welcome and necessary activity, or it may be seen as presumptuous. You should not automatically assume that the use of "made it his business" indicates that the person is acting impolitely; you must figure that out from context.