the store initially relied on the word of the gun’s vendor, JMD All Star of New Jersey, that the toys were legal for sale
...a failure of due diligence.
the prior manager failed to inform store owner Jamal Ahmed that a city inspector had written up the shop.
...another failure of due diligence.
Because of that failure, Ahmed missed a hearing, which led to the $30,000 fine
...Something sounds amiss, but skipping a hearing certainly inclines oneself to be found at fault, at maximum value.
The lawyer got Consumer Affairs to reopen the case and negotiate a tentative settlement for about $5,400.
Finally a proper action, which resulted in an approximately 80% reduction in the fine over what by now is an obviously at fault violation.
But Ahmed couldn’t afford that either, so he tried his luck at another hearing.

Who in the hell can't afford 5k? Pull it out of your commercial line-of-credit or place it on a credit card if you need to. It sucks, but consider it a cheap lesson to perform better due diligence in the future. Than, go after the vendor who stated they were legal, in order to recoup a majority of that 5k. You do have the answer in writing, no?
After the store argued that no reasonable person would believe the guns were real
Sigh, one should realize, that type of argument is a horrendous hearing strategy. Which resulted in the loss of that 80% fine reduction.