Seems like you are still blaming the user for his “very slow internet”.
How do you know the user internet was slow? Couldn’t a race condition like this exist anyway with regular 2 fast internet connections competing for the same sessions?
Something doesn’t add up.
this is a completely reasonable and seemingly quite transparent explaination.
if you want a conspiracy, there are better places to look.
Instead of saying "race condition that appears on very slow internet connections", you might say "race condition caused by real-world network latencies that our in-office testing didn't reveal" or some shit.