Members cannot be "poached" as it is feasibly impossible, everyone unfortunately has free will and has the right to think that a new group might give them a better game time. If he/she "poaches" members of your regiment be glad them gone as it means less complaining of things in the regiment that others appear to be satisfied with.
Its as bad as the "kill stealing" argument as kills cannot be stolen until the kill is awarded thus "kill stealing" is probably the worst naming of the situation more of "Taking a kill I have not confirmed yet, thus the game has not awarded me yet that I believe I can get easily, that you have just taken that opportunity away from me".
Still the same whine as 2012?
Don't worry your members have not been poached, they have simply elected that they do not feel comfortable playing in your regiment and have thus elected to move somewhere else. If they havn't moved? be happy for that fact they prefer your company over someone else rather than making any deal of it, instead just laugh, brush the chip off your shoulder and carry on.
Yes members of his regiment have free will. If they were to say leave and join 54e then that would be fine. However the idea of the leader intentionally adding and attempting persuade the members to leave the regiment and join the 54e is not.
Just read back what you said there mate, it is still there choice to leave no matter the persuasion or not. All he is doing is clearing out the members that quite clearly don't really want to be there anymore, they wouldn't leave if they had no reason to. Just because that reason comes along doesn't mean because there is another person involved it is wrong.
Does this make sales people bad people? I'm pretty sure it doesn't. If anything you should really be angry at the person leaving not the person behind the reason for their leaving. They offered nothing more than an opportunity that your member decided to take, this happens in the work place all the time where staff members are poached, has anyone really done wrong here? No everyone is actually getting something out of it:
Persuader gets what they intended to get.
"Pursuadee" gets what they seem to want.
The leader gets rid of someone who is quite clearly not loyal or putting the effort into the group as they want.
Really the person loosing out the most here is the person persuading as they tend to gain people they didn't really want ... a hell of a lot of instability there.
Remember no-body owes you anything, you started with nothing.