I don't agree with all of that.
Speaking ONLY about the afloat community, your jobs and careers are generally wide open after that first tour (a reason some go afloat, keep those doors open). Being on a buoy tender as an ensign may make you more selective to go Ops on a 175' second tour. Buoy tenders do LE too. I can think of more instance when my cutter transfered Cuban migrants to a 225'.
I had a 225' classmate who got command of an 87' following that first tour. He was also deep selected for LT.
You have the three general communities....afloat, ashore and aviation. Most of those cross paths in staff tours. All of those doors will still be open to you if you go first tour afloat. You will be hard pressed to go to a cutter after you spent 3 years in a land billet and are not qualified on a cutter. If you go aviation, you will be a pilot, so kiss commanding a cutter goodbye. The Academy used to send ALL cadets to ships....why? Because it's a sea service, AND all opportunities are still open after that first tour.
Within the communities, you can be more attractive for one thing or another. A Polar Roller Coastie may be more attractive for a 140'. A 225' JO may be more attractive for a 175' OPS job. If you were a JO on any ship, you may be one up on someone who has never been on that platform.
If you go ashore first tour, will you 100% rule out an afloat billet? No, but it's not in your favor, too many qualified people out there going after those billets.
In general, aviation is not limited until you reach a certain age or are barred for physical reasons. It's a school, so everyone starts out as a student. Once you're a pilot however, operationally, you're limited to the aviation community.
You will learn a general path for your career.....
Operational - Staff - Operational - Staff....etc is fairly normal.
Operational - Operational - Staff - Operational - Staff ....is a little more rare, may involve a JO on a ship getting XO of a 110', command of an 87', or XO or OPS on a NAG 110', OPS on a 175', 1LT on a NSC etc.
Operational - Operational - Operational - Staff - Operational - Staff... rare....maybe a JO from a ship going to a NAG 110' as XO or OPS and then getting command of an 87' upon their return.
Operational - Staff - Staff - Staff.... Not good for your career
In general you want more operational than staff time, getting qualified for your specialty...staff time involves more logistical stuff and policy, doesn't involve as much "qualfication" and in general doesn't have a path. Your staff tours CAN be related to your operational specialty.