Correct. Even if someone does not intend to be griefing a group, if they have hundreds of DCs for any reason, they are going to get actioned. There comes a point where someone who has internet issues realizes that their connection is not stable, or their PC is having issues. They stop doing the group content until they get it fixed.
Read the first line
“Without regard for the experience of fellow players” means people who have tons of disconnections - whatever the reason - even accidental. They know they have that issue because it happens happening and they keep doing group content. Then the second part addresses those who do it on purpose.
On purpose or not, someone who is leaving many many keys, for any reason, can end up with a suspension.
There is no magic “say you have an internet issue” get out of jail free card.
Very likely.
Either the player know there is a disconnection issue, or they are doing it on purpose. Either way they need to not do that anymore. The number of disconnects/leaves is pretty high I think so most players should never run into an issue.