Please see the following documentation:

This ruleset does not provide configurable rules for personal/team style or usage preferences. If you'd like to enforce stylistic rules beyond the official Terraform Language recommendations, you should author your own ruleset plugin.

https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.13.0/docs/rules/README.md

As you say, this rule/option is not included in the official Terraform reference, so it would be difficult to accept it as part of this ruleset. Please understand that we have this policy because accepting all such options would result in an unmaintainable large ruleset.

Understandable

/* and */ are start and end delimiters for a comment that might span over multiple lines.

The # single-line comment style is the default comment style and should be used in most cases. Automatic configuration formatting tools may automatically transform // comments into # comments, since the double-slash style is not idiomatic.

If it didn't say might you could argue for not using multi-line syntax for a single line comment. But the docs are intentionally permissive.

Whereas for # vs // it's emphasized that // is handled by the parser but discouraged.

So yes, this would be a "style preference" for your own ruleset vs an option for this one.