If you apply for a work permit in another member state, I would be 99% sure you will not be refused because of what happened in Poland. Just dont mention it on the relevant documents.
You'll have a record in SIS4All saying that you've got a ban from Schengen territory, combined with a stamp in the passport which essentially says 'banned'. The application for a work permit will reveal this - and it's quite possible that even attempting to gain a work permit in Schengen will be enough to land a further ban.
It's not a matter of mentioning it or not mentioning it - these things are held at a Schengen-wide level.
You can get a 90 day holiday visa in Ireland or the UK, without any background checks. Just proof of sufficent funds. While there, apply for work.
What use is this? No-one in the UK or Ireland will hire you without documentation proving your right to work in the UK/Ireland - and even a work permit for those countries won't be enough to gain access to Schengen.
There's also the issue that if he's caught in Schengen (or trying to enter!) - then he could face more serious punishment than merely a ban from the zone.
Poland should have no say at all about your visiting other EU nations. That is an incredibly stupid and lazy way to administrate...but it doesn't surprise me here.
Schengen rules are rules - if you receive a ban from one Schengen country, you're banned from the whole lot. It's the only way that open borders can work.
How do you think Spanish police are going to deal with someone who is listed as having a ban from Schengen? They're not going to invite him for tea and crumpets - they're going to invite him to the local police station in order to process his deportation.
I was just ejected from Poland a bit more then a month ago. I had filed my paperwork for temporary residence. My school kept telling me that I did not need a work permit. One day I walked back to my appartment and the border patrol was waiting for me. They gave me one week to leave Poland. I wrote an appeal but it was turned down. This mistake was my schools fault not mine, however, I will pay the price. I never tried to work illegal. I filed my paperwork, had a bank account and even paid taxes.
You need to get an immigration lawyer who is capable of dealing with this. It'll cost you, but it's possible to get such decisions overturned *if* you get someone capable of dealing with it.
Incidentally, I've heard of the American authorities deporting people from the USA at gunpoint who have overstayed their visa waiver. You should be glad that the Straż Graniczna allowed you a week.