I am well aware of anti poaching agreements between partners or consulting agencies and clients. I am currently working for a consulting company (full time) and in the past I was an employee at AWS ProServe.
The contract states you can’t solicit employees under that arrangement. But either side’s employees are free to proactively outreach.
I’m not referring to “consulting companies” that are basically doing staff augmentation.
Neither is the case here
It isn't about poaching. It is about how vigorously you'd be protecting the interests of your company A in a deal with company B when simultaneously negotiating your personal offer with the company B, especially if it is [even if just implicitly] packaged together i.e. "the offer happens only if the deal happens." You don't see a conflict of interests here?
There is no evidence that any of these companies had contracts with the acquiring companies before reaching out to the employees.