As a float plane pilot, I can tell you that we are more worried about you than you are of us.If you keep tabs on where they are taking off and landing,there should not be a conflict.
Are they running a charter service or sight seeing tours? How many take offs and landings per day are there? we pilots are almost obsesive about being good neighbors because we face complaints on a daily basis. An airport or a seaplane base might exist for 50 years and then some bozo attorney buys property near by and spends his spare time trying to shut the operation down.It doesn't matter that this guy was fully aware of the airport at the time of purchase in his little mind, it has to go.
If you would like to educate yourself in the ways of seaplanes, try www.aopa.org and link to the seaplane assoc.