Bootcamp is a stressful place where I'm sure they didnt do multiple repeat studies or let you take it at home then slapped you with a hypertension diagnosis.
Buy a BP cuff and measure yourself at home a couple of times to confirm theres is something actually wrong with your parameters. Its amazing how stress, being measured the moment you walk in the door and people yelling at you will raise your BP outside 140/90.
I'm not saying the docs are wrong, but the medical world does BP measurements quick and lazy.
However, NAMI waiver guide is pretty clear on this one:
p.51
"Blood pressure exceeding 139 mmHG systolic or 89 mmHG diastolic is CD and a waiver will not be recommended"
I'm a victim of bad white coat syndrome that developed a year or so into the navy, so I've had plenty of initial readings well beyond 140/90 as an aviator..... but after a couple of minutes and a 2nd reading, everything calms down into range. Pretty much if you can show you don't have hypertension, you'll be fine and likely wont need any waiver.