Assuming it was legitimate, 282 self-selected responses from a company with tens of thousands of employees wouldn't pass even the most basic "is this poll statistically valid?" test.
It totally would. Statistically, a sample size of 282 out of a population of 60000 is pretty good.
If this test was authentic, we would be 95% sure that the true percentage of the population who think that the memo is harmless is between 47% and 60%.
Otherwise you could run a poll "Who thinks [minority] should leave the USA?", get a high "yes" response, say "THE POPULACE AGREE!" but then discover only racists/whatever have replied because Breitbart/4chan dogpiled the poll - which would make it 100% invalid, no?