I just hope that he continues to pay his craftsmen so that your construction can proceed.
This could be secured by agreeing with the general contractor to pay the craftsmen directly (à compte from the payment schedule), i.e. to transfer only his margin to him from the respective installments and pay the costs directly to the invoicers.
Insolvency pay exists, but for employees, not for subcontractors.
I have worked in the insolvency sector and will give you a brief piece of advice: resign
I would have also advised that if an insolvency administrator had been appointed. But here self-administration was allowed.
Certainly, naivety would be out of place no matter how honest the guy is, but fear as well. Unfortunately, insolvency administrators have a financial interest in being more undertakers than healers. They get paid just as well for an administration as for a liquidation; a rescue means losing clients for them without a success bonus (because there is none) to compensate. As sad as that is, it makes clear what is better for them personally. Among lawyers there are altruists and Porsche orderers; unfortunately, the latter specialize in insolvency law more often.