It slid last week so it's good…right?

It's clear from inbounds ski area operations that sufficient avalanche control work is capable of rendering normally avalanche prone slopes safe-enough to sustain ski area operations even in deep storm conditions, so it's possible that your guide was correct. Making expert calls is the realm of experts; some will argue that there are no experts.

Caveat skier.

Below is a video of "Employee housing" going big yesterday at Crystal.    I saw large crowns and slides down to the old/bad layer in Niagras/O-Meadows nearby when this terrain opened a few weeks ago.  I didn't notice big crowns in EH.   Did EH slide down to that pre-storm layer, can't say.   Just wanted to point out that this is a slope regularly controlled by experts and people have been skiing it for weeks.  But conditions changed (ie. rain, warm), so yesterday control work produced different results.

Yea but they re-bomb those slopes or ski cut them after a new storm loading event prior to opening the area. Sometimes it slides, sometimes it doesn't. If they, the experts truely knew whether or not a slope was safe, why waste the cash and place even more toxic chemical explosive residue into the enviornment? I think that i have offered factual proof here on tay that some commerical guides, your experts coming out of ski area patrols, hide their client related avy incidents. This creates a false sense that the experts know what they are doing and does not further the goals of education or client safety.

Because no "Expert" is going to point at slope in the winter and say it's 100% safe

I've had "experts" tell me a slope was 100 % safe.  I skied it but that was because I thought it was "probably" "pretty" safe.  A few years later up there way north of the boarder at the same place, "experts" were guiding a bunch of folks and a bunch bit it...I assume they were marching fairly close just like on my trip.  No Way any  body knows when a slope is "absolutely" stable;  at best the calculation of somewhere near "low" risk is possible....everybody should be "calculating their own risk" and not leaving this to somebody else, IMHO...

The use of the word expert in this sport is over used

So much for the skier compaction theory ie...Hamburger Hill Chair 6 Crystal.
A few years back there was an eye opening picture of the Moguls under the Glacier chair at Blackcomb where the slope had given out to a similar type avalanche. That is an eye opener when hard pack moguls pull out like a slab avalanche!