I'd love to hear more about it if it's true, but that'd be a very unusual design and also terribly bad. By searching I mean literally just seeing the search results, not moving any forward in the booking process. If searching pulls from inventory, then on any given search I'd be blocking inventory on tens (or hundreds) of flights, which seems too bad to be true. This also doesn't seem to align with past experiences when I was looking at very limited inventory (e.g. 1 seat left on IROP days or stuff like that) where I probably had searches ongoing for the same flights from different sites/devices at the same time for any given itinerary.

In any case, in this instance the availability was O7 on Expertflyer, so even if somehow my search was blocking 2 of those, they would still see the rest.