you’re right about the math, no argument there. expected time to the next block is ~10 min from now, doesn’t matter how long it’s been. memoryless.
but that’s not what the timer is showing. it’s not a forecast of the next block. it’s where we are in the cadence.
10 min is the protocol’s target. difficulty retargets to hold that mean. so we start the clock at 10:00, the network’s heartbeat, and show how far the current beat has run. once it passes 10:00 it just counts the delay.
the question i’m answering for the user is “are we on time or running late,” not “when is the next block.” that second one i won’t predict, because you’re right, you can’t.
simplest honest read of the current status. that’s the whole idea.