You probably won't find a bigger fan of Gordie Howe on HFBoards (at least outside of the History forum). And I still voted "Yes". Two reasons:
First - I think that, if Howe was still alive, he'd be cheering Marleau on. We know that Howe was very supportive of Gretzky leading up to #99 surpassing him to become the NHL's all-time leading scorer. Howe actually spent several games travelling with the Kings, so that he could witness the event first-hand. In an interview before one of the final games, Howe said "I'm excited for him" and "I'm extremely proud", even comparing the pride that he felt to what Walter Gretzky must be feeling. If he can support Gretzky taking a far more significant record, why wouldn't he support Marleau taking a relatively minor one?
Second - I think it might help change the "narrative" about Howe's career. Many people seem to be under the impression that Howe was pretty good for a really long time. Someone else holding the all-time games played record might allow people to focus on some of the things that Howe accomplished that are way more impressive (six Hart trophies, six Art Ross trophies, six playoff scoring titles, five goal-scoring crowns, setting the single-season record for points in a playoff run, having four of the top five highest scoring seasons in NHL history at one point, etc).