On $*:TEXT:^(\.c|!c|\.command|!command)$:#help: {
(or) On $*:TEXT:^([.]c|!c|[.]command|!command)$:#help: {
(or) On $*:TEXT:^([.!]c|[.!]command)$:#help: {
(or) On $*:TEXT:^([.!](?:c|command))$:#help: {
  echo -a The command $regml(1) was typed.
  ; note that '.' is a special wildcard character in regex, so it
  ; must be escaped with '\' or presented inside a character class '[]'
  ; see how alternation works with pipe '|'
  ; see how grouping_with_backreference works with '()'
  ; see how grouping_without_backreference works with '(?:)'

Well. At least I won lunch.
Good philosophy, see good in bad, I like!