Depends on what he has played so far and what his decklist, but let's we can do some guess work. Going Trumps' way, if the golem survives (3/64), it's guaranteed lethal.

Now for chat's situation. Trump is at 5. SS only needs 3 damage with HP. Let's just assume this decklist or something along those lines (I'd swap Flame Juggler for Wolfrider). Outright outs are: Quickshot, Kill Command, Eaglehorn Bow, Arcane Golem, Leeroy, Wolfrider, Animal Companion (33%). Combo Outs: UTH + Abusive, UTH + Glaivezooka, Knife Juggler + UTH (50%), Argent Horserider + UTH, Argent Horserider + Glaivezooka, Argent Horserider + Abusive. Let's do some guess work for what was previously played. I'm assuming Turn 7 based off of Trump's 8 mana, could be wrong if another AG was already played. Let's say he's drawn a total of 11 cards + 1 trap off a scientist. Of those 12 cards, 4 are in hand, and 18 cards are in his deck. There's a 40% chance (not factoring if he's already played them) he's drawn one of his finishers (i.e. Leeroy), there's a 14.7% he's drawn any of the combo kills. Rarely do you burn Quick Shot/Kill Command so early without guaranteed lethal so he probably has at least 3/4 of them unplayed...

I'm going to stop here as it's getting late and I'm starting to ramble and making too many assumptions. In short, it's extremely likely that SilentStorm has lethal (probably 95%+) without AG, and this situation is only relevant in 3/64 of the cases (in which AG lives w/o lethal) anyhow. As such, SS would only need to be 33% likely to have lethal to justify Trump's solution over chat's for the additional 1/64th advantage.