[binions]

In that particular hypo, there will be no more betting if you call since both of your foes are all in. So there are no implied odds.

Moreover, the book is incorrect to assume you have a full 8 outs. There is some chance that one of the players has a flush draw plus a pair or gutshot, etc. On the other hand, they may not have a flush draw.

Since there is a chance but no way to tell, you disocunt your outs. If no one had a flush draw, you have 8 outs. If someone has a flush draw, you have 6 outs. Based on that, I would argue that you have 7 effective outs with 1 to come.

Finally, the book is even more incorrect to assume there are 46 unseen cards. Against 2 foes when you give yourself effective outs based on a range of hands they might have, you are really dealing with 42 unseen cards. So, your odds are 35:7 or 5:1 against.

The answer remains the same: can't call.