You're conjoining two issues. There's the CO scabs, who were forgiven by ALPA, and let back in. They had to pay back dues and are considered members in good standing. Not much you can do about it.
Then there are the other scabs still out there, who haven't been forgiven. Those are the ones we're talking about. And again, it's not a Jumpseat war. That takes a concerted effort by a pilot group. You're describing a one off incident that may effect you personally. You're call but I would never ride a scab's Jumpseat. Hell, I took myself off a flight and waited for a later one when, introducing myself to the captain, discovered it was JC Lawton. That dude can burn in Hell, for all I care.
For the record, I did have to allow a scab to jump once. Dude was an Eastern scab, but was now an FAA ASI. No chance to deny him. Funny thing was, as he was deplaning, here comes another FAA ASI, who was a rEAL, who just about beat the ever loving snot out of him. They had an epic, foul vocabulary laced shouting match on the ramp.