I’m assuming you are using the WP Discourse plugin.
You can publish a post from WordPress to Discourse without enabling Discourse comments for your post. Do this by not selecting ‘Use Discourse Comments’ on the WP Discourse Commenting setting page and then selecting ‘Publish post to Discourse’ on the WordPress edit page. This will publish your post to Discourse and allow you to have Discourse comments on the forum and WordPress comments on the website. When Discourse comments aren’t being used for WordPress posts, the plugin doesn’t add a ‘continue discussion’ link to the WordPress post. It wouldn’t be to hard to set it up to do that though.
You can set the ‘Auto Publish’ option on the plugin’s Publishing options tab. With this set, the ‘Publish post to Discourse’ checkbox will be pre-checked on the post edit page. It can be unchecked there if you have a post you don’t want to publish to Discourse.