Nah...the guy at the shop was just trying to sell you something different.
Personally I use Kroil, but there is nothing wrong with using Hoppe's #9. I use RemOil, BreakFreeCLP, or just plain old motor oil for lubrication afterwards. (shh...I don't want to start up the old motor oil vs gun oil debate again.
He was probably concerned about the anodized coating on the alloy grip frame. Some cleaners that have acetone can attack some aluminum alloy coatings...IF you leave them on the metal too long. If you're just using them to clean and then you're wiping down and oiling afterwards you'll be just fine. I've cleaned a couple of Ruger alloy grip frames for nearly 15 years with just Hoppes and it didn't damage the finish at all.
Whatever you do, if you do need to do any heavy scrubbing on your stainless pistol don't use regular steel wool. It will embed little particles of regular carbon steel into the stainless and it will rust. Use bronze wool, stainless steel wool, or scotchbrite type pads instead.
And don't use any of these on your aluminum grip frame either because all of them will scratch the coating. Just use a rag or patch to clean these parts.
Tetra is one of the safer of the new aerosol spray products that won't damage these new-fangled paint/poly/teflon/etc finishes on a lot of the newer guns.
Is it safer than Hoppes9? Nah, Hoppes9 is basically 90% kerosene and ethanol with a couple other old-school petroleum solvents. It has a tiny bit of an acetate chemical (works like acetone) but it's not very potent.