My guess is that if there's a battle of wills that's going to occur, the game will win. It's easier to change a name on a web project than an iOS game. There's months of advertisement that've gone in to Loren's Letterpress at this point.
Does it matter?
Not overly so, but it does make it hard to be discovered or searched for, especially with the months of links and reviews for the iOS game boosting it in search engines.
It'll matter when the blog guy wants an iOS app and has to call it "LP MAKER PLUS" or something dumb.
Setting aside any legal issues, it just seems odd and probably not in the OPs best interest to have a name that is so strongly associated with an extremely popular mobile game.
Pointless trivia: In the UK, throughout the 80s and 90s there was both a (usually lemon) kitchen cleaner and a lemon juice called Jif. It didn't seem to cause any problems, although the kitchen cleaner became Cif for unrelated reasons.