I think it qualifies as pseudo differential becuase you don't have a high impedance tail current source to reject CM signals. But is differential.
Anyway, this will not give you even a decent performance in a flash becuase:
- kickback noise at latch will upset refernces and input voltage;
- no preamplifiers means you will have a lot of metastability problems => wrong codes at the output.
- comparator have large offsets (small transistors, unmatched charge injection from switches) => wrong codes again.
A good flash has a few low gain high speed preaplifier stages (simple differential pairs, gain = 2-5) in front of a comparator.