Yeah, I can personally testify that not all ex hold poolers were contacted.
I was one of the last to get in in 2012 and therefore one of the last to drop out so when the Airbus recruitment was announced I, rather frustratingly, emailed the recruitment team as advertised on the application website.
I was trying to put some feelers out as I'm Boeing rated but wanted to update them on my flying hours, company I'm now working for, etc etc and see what the situation at their end was. I received an email straight back saying thanks for the email, however, as I didn't have a 320 rating I wasn't eligible and that they don't keep records on file(!?).
Was a bit of a kick in the teeth a few weeks later to hear through friends that several non-bus rated ex-poolers had been contacted.