I think it's a parent's job to be worried all the time. He does seem overkeen. Probably still under the illusion that one can prove oneselvf to the individual one is interested in and convince them to reciprocate. He'll learn. Meanwhile, in your shoes, I'd advice your daughter of the possible dangers and suggest she be very very clear to him what her position is; and how it isn't going to change, so can he stop being so overly pushy/helpful. He's probably harmless, just trying to win fair lady, but worth her making the situation very clear.