Re: "each cofounder had been hired individually – and therefore TUPE didn’t apply"
If there is a legal loophole to be unfurled then that tends to trump any sense of moral justice (with most judges anyway). Look at the success of "Mr Loophole" in the motoring arena (I'm not a fan of people getting off lightly on drink driving motoring offences as drink driving is dangerous to other road users / pedestrians & needs proper punishment as a heavy vehicle at speed is very dangerous (do some simple kinetic energy sums))
Always worth a (slightly out of context Billy Bragg lyric)
"And the Judge said, "This isn't a court of justice, son. This is a court of law."