Of all the setups swim has owned he's found that vaseline is the best, it doesn't clump up under pressure or under high temperatures.
This is the first that I have heard of this. One would have to wonder why professional chemists use silicone grease if petroleum jelly (Vaseline) is better.
Swim isn't sure, but there have been a few rumours about that the silicone can leak into the setup and cause contaminations.
And so could petroleum jelly. The reason that you have heard this about silicone grease and not petroleum jelly is because siicone grease is what professional chemists routinely use.