According to the paper, their laser pulse rate is 500kHz; if they're writing a single 1 bit per pulse, and half the bits are 1 bits, and there's no coding overhead from something like 8b/10b, that's 125 kilobytes per second, so 10 seconds per 1.2 megabyte 5¼" DSHD floppy. At this rate, filling the 360-terabit capacity of the disc would take 11 years. You would not expect such a slow storage system to be able to compete in the market with 50-megabyte-per-second SD cards, unless data retention of centuries or more was a key selling point, so the fact that such storage systems have failed in the market provides no evidence against the claims made in the paper.

Bubble memory, similarly, does work; it was just too slow to compete with DRAM and not dense enough to compete with spinning rust, except in a few niche applications.