As far as I am concerned, if a barrel has a minor bulge in the choke section, still has some existing choke present that must be removed for a choke tube installation, and once that is completed- does not show any internal ring below grade, there is probably little chance of metal problems with a choke hole since the tube is primarily responsible for it's own strength.
The tube should not depend on a large amount of support from the barrel (even though it provides all of the retention), but this is my opinion based upon when I install my own custom chokes and barrel threads.
I can personally ensure that the metal remaining is not very thin (especially if a plain barrel needs bead retention) and that the portion of metal used for the threads also includes some of the un-bulged metal area.
Some barrel steels may be more susceptible to cracking when expanded a large amount, but no barrel is expected to crack if expanded a slight amount, or else the metal and heat treatment were a sub-grade choice for barrel construction.
Barrels had been expanded for choke tube installation in the old days when Winchoke was the only basic game in town for almost all shops before custom and aftermarket chokes became commonplace. An expansion is a twin to a minor bulge and only differs in the speed and concentricity of formation.
A bulge may be more lopsided at a thinner section of a barrel but will not be always easily/visibly noticed. Always the potential for exceptions to alter the typical conclusion.
I never saw an expanded choke installation that was properly done have choke hole separation from the barrel or any other mechanical issues present. Choke hole problems come from installing a choke offset/crooked or leaving one side of the barrel (or all of the barrel) too thin by squeezing a choke in that was too fat for the barrel.
That is why I only do custom choke installations or precision factory replacements, since I will not be a party to installing or encouraging the use of aftermarket choke installations done with tooling that has some versions of dubious design. I won't be accused or blamed for something I've never done, ever, unless it is an accusation caused by a mental firstname.lastname@example.org