If you knew that helium balloons of the type usually used by people for enjoyment and/or celebration, by releasing them singly or by the hundred or thousand, cause death and suffering to many species of marine life would you use them?
Question seems entirely hypothetical.
Helium is mostly recovered from natural gas fields as a by-product (by fractional distillation).
The gas itself simply evaporates to space once liberated.
It comes from radioactive decay of other heavier elements.
The only mechanism I can think of, is that if people actually let the balloons go, and they explode in the air, and the balloon rubber or mylar falls back to earth, then some animals may ingest it and may suffer bowel complaints as a result.
But in the big scale of human pollution, I would think it was a very small contributor.
Activities like dumping the garbage from New York City at sea does a lot more damage – introducing massive amounts of plastics and heavy metals into the marine environment.