Totally agree - but that is just one of Umunna's many remarks on the Lib Dems, stemming right up to his time in Change UK. His talk of switching to another, safer, seat now, seems not to agree with ideas that he didn't need a by-election because his electorate were so supportive of him. I think if you quit your party, you should have a by-election asap.
Umunna himself may well be a very talented man - he certainly comes across well in interviews etc, and as an MP if you're not a bastard I can see that you would think you should join the Labour Party (you've got to be pretty fucked up to want to be a Tory MP). When he announced he was running to be Labour leader ages ago I thought he was shoe in.