Yes, that is how bankruptcy works.
Don't forget the plant DID NOT WORK. Almost all that money was flushed right down the toilet by BIOAQ. The assets were purchased for $4.3 million, with the buyer then spending tens of millions in new funds in an attempt to fix BioAmber's screw-ups.
And yes, it IS a "normal deal" in bankruptcy. If the plant were worth more than that, BioAmber probably wouldn't have gone bankrupt, would they?