There is nothing new under the sun in that respect, since at least the A340 days NB Captains have bid to senior WB FO spots when their seniority on the larger equipment allows them to work 9-12 days/month for a somewhat minor (after-taxes) pay cut.
In the course of a pilots' career it makes more sense to bid NB Captain before WB FO for a few reasons:
1) The airline adds a few extra hoops to jump through for a pilots' first command position at the company and that can be easier at 30-40 years old than at 50+
2)The NB blocks have a 16 days/month cap whereas the WB blocks don't, so Jr NB Captains can actually work fewer days per month than Jr WB FO's.
3) Earning more money earlier benefits the pilot financially.
