My advisers did not want to be coauthor of my accepted journal article
There are a few different situations that could lead to this:

Most plausible case: Your supervisors determined that in accordance with the standards of your field, they do not count as coauthors.
Different fields have different customs concerning whether supervisors are assumed to be coauthors of papers resulting from the supervised work. If you worked independently and your supervisors agree, then being a single author on the resulting paper will always be reasonable. Since you mention asking them only at submission stage, it does sound as if their involvement is limited.

Your supervisors really ought to be coauthors by the standards of your field, but declined to give you an (unfair) advantage or similar.
This is problematic from an ethical perspective. Having another persons consent still doesn't allow an academic to present their ideas as ones own. A carefully worded acknowledgement might work.

Your supervisors declined because they are aware of flaws in your paper, and don't want to be associated with it.
While one would hope that peer review would spot problems, there is no guarantee that it does. If your supervisors are aware of any major flaws, it would be your ethical responsibility to find out and either fix the paper, or to withdraw it if it is unfixable.

The manusscript is sound, but your supervisors are under political pressure to not associate themselves with the results. (pointed out by nick012000 in the comments)
Probably no ethical concerns about you publishing here, unless the political pressure is there for very good reasons.