Quick question while on this subject.
Can a single escort with a pair of stasis webs sling a freighter to warp through the bumps ?

Bumping is an allowed game mechanic. Even so I would be infuriated if I were forced to sit there for an hour without being able to log off. At least they finally got around to putting you out of your misery.

My understanding is that, even if safe logoff is unavailable and the emergency warp fails, the ship will still vanish 15 minutes after logoff. So as long as the DPS to kill the freighter doesn't arrive before that 15 minutes is up, the freighter would survive.

Or is there something I'm missing ?

yes but a pair of ships coudl do it.. by counter bumping the machariel to give the freighter some needed seconds. Not guaranteed, but better than nothing.

Would webbing the machariel achieve anything. Grab any old cheap cruiser from the lcal station' something like a celestis with 5 mid slots. Fit as many Webber's as you can and when the machariel finishes a bump stack 5 Webber's on it and just shut down its ability to bump again. You'd have until concord arrived to get the freighter into warp. Worst case concord already being there when the gank ships arrive will make the time the gank ships have to do their job a lot shorter?

I'd say this would fall under harassment in terms of bumping. With multiple attempts to leave and even to log off over the course of an hour while they just kept harassing the freighter.

"persistent targeting of a player with bumping by following them around after they have made an effort to move on to another location can be classified as harassment"

While it will involve inconvenience, we will have to see that one actively tried evasion before we consider someone being followed around and harassed. Merely changing belts in the same system or moving a few thousand meters to another asteroid would not qualify in this regard. Ideally you would move to other systems and more than just one or two jumps to avoid being found again quickly, requiring some effort to locate you again (i.e. through locator agents).

Freighter was trying to move to another location, persistent bumping was preventing that. Do try to keep up.

moving a few thousand meters ... would not qualify in this regard. Ideally you would move to other systems and more than just one or two jumps to avoid being found again quickly,

The freighter could not move because of bumping.

The guidance makes clear that some bumping is acceptable but excessive or repeated bumping is not (I even underlined the word you seem to have missed).

Using game mechanics to hold the freighter for that amount of time to has be wrong.