So, unfortunately, since Lucas already redshirted he'd have to apply for a sixth year exemption and a hardship waiver. Very unlikely to be granted unless he misses two years due to injury.
I am not an NCAA expert, just my take on reading the rules:
They modified the five-year rule waiver rules, but the implementation in the past has seemed to be very unpredictable. the rule book says:
The Committee on Student-Athlete Reinstatement, by a two-thirds majority of its members present and voting, may approve such additional waivers to the five-year rule as it deems appropriate (see Bylaw 30.6.1 for criteria).
In 30.6.1 instead of saying "two years due to injury", it says "reasons that are beyond the control of the student-athlete or the institution, which deprive the student-athlete of the opportunity to participate for more than one season in his/her sport within the five-year period".
There is a criteria which is more directly listed now in the rules book. However in the past SAs who objectively more than met the criteria were denied and SAs who objectively did not meet the criteria were approved. If two-thirds of the members present vote to allow a sixth year it is granted. As with many things related to NCAA rules enforcement sometimes the rules seem to mean whatever the committee says they mean instead of what is actually written.
With LJ, if he can prove that he missed an opportunity to participate in at least part of another season then he could apply for the waiver. From past years, I have no idea how the committee would vote. Probably not a good chance, but it isn't a zero chance.