There are a few errors with your code but I think the one that is slowing you down the most is that there is no informat "MDYHMS". That's causing many errors to be written to the log and that's what taking so long. Take a look in your log and see if I'm correct.
Try this instead:
minDate="02/16/2021 12:23:09 AM";
current data table() << Select where( :column 1 <= informat(minDate, "m/d/y h:m:s" )) << Hide and Exclude();
However, even that's more than you need. You can avoid the informat all together by using a datetime constant (you can read about them in Using dates, times, datetimes and durations in JMP).
minDate="16Feb2021 12:23:09 AM";
current data table() << Select where( :column 1 <= informat( minDate ) << Hide and Exclude();
Finally, you had a spurious [] after your Column() designation. I don't think that's useful here.
-Jeff