It is not a requirement to get a 4.0 your first semester of college to be a successful re-applicant. (though it certainly won't hurt). Take a rigorous schedule and make good grades. 2 local folks just started PS that were re-applicants and neither had a 4.0 their first semester in college.
There are a number of reasons to start with Calculus I - ensuring you have a truly solid baseline understanding is one, but it is also easy to fall into the trap of 'oh, I already know this' and not do enough work to obtain the easy A. I have also heard people say the AP Calculus is not as rigorous as a college level Calculus I class. I would also suggest that if the Dean suggested Calculus II, he/she is probably pretty good at making those type of judgements. They (as a general rule) won't put someone in a position to fail.
Curious as to why starting in Calculus I is an easy A and starting in Calculus II is a B+.
If you have been down this path before, you should realize keeping Plan B as an open option is important. The 2021 class will be no less competitive than the 2020 class (though I do believe re-applicants are looked on quite favorably). If you are ready for Calc II and Chem II, I would suggest moving on and taking them and if you think it will require extra time to get A's in both, then take 14 hours instead of 17. Whether at State U or USNA the goal is to graduate starting out ahead puts you a little closer.
DD scored a 5 on the AP Calculus exam and a 3 on the AP Chemistry exam. She is at PS now and based on the tests USNA administers, she has validated Calculus I and Chemistry I. Though she currently wants to pursue a STEM degree it won't include being a ChemEng, so putting Chem I in the rearview mirror is/was her goal.
Obviously, you have to decide what is best for your situation, but if professionals (the Dean) are telling you Calculus II, that is more valuable input than a bunch of folks you don't know on a message board.