I'm going to stick my neck out here...
1 I'm NOT advocating using an unguarded tablesaw. OK?
, but
2 I don't think that the average US style crown guard is very good at protection. Yes it's relatively good if you put your hand down from above, but unless you faint while operating it, I suggest that it is more likely that your fingers will enter from the front or side. So I see no reason why the guard shouldn't be removed provided that it is replaced with a method which is at least as good, and preferably better, that the protection offered by the manufacturer.
So, if you are going to cut tenons this way, you need to design your jig so that you can cut tenons whilst keeping the blade itself untouchable.
I'd do this by building a sliding carriage that travels in one of the mitre slots, with the workpiece clamped to an upright face, and the handle on the other side of the face. The face would be long enough and high enough so that the blade could not be reached from that side at any point on its travel, and I'd have another vertical board mounted to the fence on the other side of the tenon, close onogh to the blade to prevent finger access, but clear enough to let the tenon cheek fall without getting kickback.
I do have a jig that I built when god was a boy, from plans in FWW, but although it works quite well, it is totally unguarded, and now it scares me, so it's actually many years since I've used it.
I have actually been thinking about this for a little while, as I have a new tablesaw with a crown guard, and a video to make! But this jig won't be in the video, nor probably the second one, but if I get round to doing one specifically on the tablesaw, I'll probably develop such a jig simply because there are so many dodgy versions already published.
In the meantime, why not cut them with a router? There will be another such jig in GW in the next couple of months or so, I believe.
Cheers
Steve