as with all such questions: ask at a consulate or embassy!
That aside, ESTA is a tourist visa program, not a work permit. Therefore I'd expect it to not be valid for business travel (which yours would be). While they may not mind someone using it to attend a tradeshow for a few days, or a conference, as an agent for a foreign company, your plans are quite different. You're going to be putting a US resident out of a job (or preventing one from getting a job), which is the very reason foreigners need work permits as companies have to show they can't get local people qualified before a foreigner is allowed in to perform the work (or that's the theory at least behind such things).
But as said, ask at an embassy or consulate.

As with all such questions: ask at a consulate or embassy!
That aside, ESTA is a tourist visa program, not a work permit. Therefore I'd expect it to not be valid for business travel (which yours would be). While they may not mind someone using it to attend a tradeshow for a few days, or a conference, as an agent for a foreign company, your plans are quite different. You're going to be putting a US resident out of a job (or preventing one from getting a job), which is the very reason foreigners need work permits as companies have to show they can't get local people qualified before a foreigner is allowed in to perform the work (or that's the theory at least behind such things).
But as said, ask at an embassy or consulate.