That is what they are going to do.
I'm staying away from this as I feel every plate on every truss joint should be inspected and I don't have the attention span for that.
Looks like pressed plate not nailed plate. And yeah, storing a bunch of steel in your attic is likely to overload those plates. The tabs are small enough that they'd definitely pull out before they sheared/ripped off the plate.
Was there any evidence of differential movement in shear? between the roof structure and the attic floor. That scrabbled tearing on the top surface looks quite odd, as though the plate sprung from the bottom surface before finally giving way / springing off. Guess we won't know what happened once the first one went
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
When truss plates are overloaded they typically curl and pull out. I've never seen one come out as cleanly as that one. Usually they pull some chunks of wood out with them.
I agree that every plate should be checked. Especially at the heels.
Do you have any more pics or information? I'd love to know more about it.
One thing that you won't know for sure is how much deflection occurred with the walls on either side of the trusses since the roof load is no longer directed fully downward by the trusses. This could mean that jacking the up trusses wouldn't necessarily restore everything to the as-built configuration.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!