It’s telling, isn’t it, how easily someone can be a Conservative MP one day, and a Lib Dem MP the next? No change of beliefs is needed. No change of mindset. The MP carries on exactly as before, saying the same things. One could also imagine such people joining New Labour, before the Corbynites took over. (And of course, this has happened, Robert Jackson and Quentin Davies, for example, in the 2000s.)
Why do these people choose to join the Conservatives rather than the LibDems in the first place? The reason is that the Conservatives are a successful party. They have more money. They win elections. Their enacted policies (as opposed to what they say) have for years been pretty similar to the LibDems, so the prospective MP thinks, join the winners.