Popper sounds like a dude. We shouldn't confuse this apparent irascibility with dogmatism. He was passionate about his ideas: he published them and read criticism of them. He changed his mind about the testability of evolution, and other things.

Intellectual humility is not the same quality as personal meekness and geniuses have always had difficult personalities. Philosophers doubly so. How could it be otherwise? How can one create new stuff if one is too agreeable and too susceptible to groupthink?

Btw, the reason falsifiability doesn't have to be falsifiable (by experiment) is that it isn't a scientific idea; it's a philosophical one. It is potentially 'falsifiable' by criticism, however.

The best modern Popper proponent is David Deutsch. See his books The Fabric of Reality and The Beginning of Infinity. They're both packed with interesting ideas and arguments. He says that Popper did indeed solve the problem of induction. And here's a recent paper of his on the logic of experimental testing: https://arxiv.org/abs/1508.02048