There’s another option. Since the philosophy is that Markdown is supposed to be lightweight, not a markup language, and intended for natural human consumption (in contrast to SGML/HTML-style formats), I believe it’s fine and natural to fall back to ASCII art for special cases.
For this particular task, character art is natural. Thus, just indent your table with four spaces, format it nicely for readability, and Markdown will just treat it as pre-formatted text, and both sides can stop fighting each other.
For example:
| Sequence | Result |
|-------------|---------------------------------------------------------------|
| `a?c` | Matches `abc`, `axc`, and `aac`. Does not match `ac`, `abbc`, |
| | or `a/c`. |
|-------------|---------------------------------------------------------------|
| `a*c` | Matches "ac", "abc" and "azzzzzzzc". Does not match "a/c". |
|-------------|---------------------------------------------------------------|
| `foo...bar` | Matches "foobar", "fooxbar", and "fooz/blaz/rebar". Does not |
| | match "fo/obar", "fobar" or "food/bark". |
|-------------|---------------------------------------------------------------|
| `....obj` | Matches all files anywhere in the current hierarchy that end |
| | in ".obj". Note that the first three periods are interpreted |
| | as "...", and the fourth one is interpreted as a literal "." |
| | character. |
|-------------|---------------------------------------------------------------|
… and done.