Can't understand what correlation you are trying to make.
I would say yes this is Oda creating fake tension.
I mean we already knew how many marines were going that way. There is literally 0 reason for him to hype that even more by having that incident claiming.
I guess he got worried people would hate how much we are changing views in this arc. We were at Egghead and then we moved to Winner Island, later Elbaf, then Hachinosu, and he used that fake tension to keep people interested in Egghead while he was developing the other plots.