ahhh the lessons we learn the hard way playing with mary jane.....
first, are you looking at Acitve Duty - or Guard / reserves? going from the Navy Reserve to Army Guard / Reserves doesn't take a 'blue to green' program. the guard / reserves is a different monster all together. there WAS a 'blue to green' program for AD AF members to go to the Army, but that program was suspended well over a year ago and to my knowledge has not been opened back up because of the army meeting recruiting and retention goals.
did the ARMY recruiter say you COULD NOT JOIN and had to wait 6 years (which would make you 29?)? it sounds like the Navy recruiter told you that. it appears the Army recruiter told you that you could not join PERIOD.
the military does not make a lot of exemptions for people with drug convictions on their record - regardless of your age at the time. regardless if your record was 'sealed' or not. regardless if it was 'expunged', regardless if you had a pardon. regardless if you want to go guard / reserves / or active duty. Quite honestly i am surprised the Navy would even take you, because their standards are almost as high as the Air Force, and if the Army sent you away - that is NOT a good sign, and i don't see a good outcome for your ambitions.
first, talk to the army recruiter again. Are you permanently DQ'd from army active duty service, yes or no? are you permanently DQ's from Army guard / reserves, yes or no? if the answer is YES (to both) - then you are DONE with the Army and there is nothing you can do to get a waiver or exemption - you're toast. if the answer is NO for either - get the details of what you'd have to do, how long you'd have to wait, how to attone for your sins, etc. and then make a decision. is the guard / reserve (a part time gig) acceptable? you will NOT be able to go active duty later no-way, no-how if you go guard or reserves now (you'd be prior service, and that is practically a death sentence if you later want to go active).
second, if the Army recruiter says you are done with them (i can guarantee you have no chance with the Air Force), and the NAVY is the only gig in town (which would surprise me for a drug conviction), then GO WITH IT (so don't tell him where to go yet). the only question then would be naval reserves, or active duty? remeber: go reserves now, forget about active duty later. will not happen.
right now your options are limited, might have to take the best offer on the table.
23 years air force, retired special operations command