I think he was a very overprotective person. He actually loved his daughter, and he wanted the best for Megan. I think of him as a fifty- year-old man, not very tall, but fit, and he surely wore some smart clothes since he was the shop's owner.
He surely thought of Huw as a poor person in the future, and he wanted to protect his daughter from that fate, then he decided to keep Huw's letters.