I'm sorry but I don't think I've ever laughed more at something in a chess book, it's the last part after the comma that really gets me.

I have another book by Gormally that I've never liked much either.
Excerpt from:
https://forwardchess.com/sample/the-scheveningen-sicilian-revisited I think a lot of the reason for the poor results and reputation of the Scheveningen is due to the gimmicky h6-h5 on move 8. If black moves 8. ... d5 instead white gets even slightly less winning percentage than the Najdorf, The computer evaluates this as 0.4 as opposed to 0.7 for h6-h5 at depth 47. But it's finding a practical way of winning that seems to be the problem for black in this line.
If you look at the few Scheveningen games in recent years by the top players on lichess' masters database they almost invariably play 8. ...d5. Duda scored a win for it against Nepo in 2018 St. Petersburg - but beware that was a blitz game as some of these games are.
According to lichess masters database also there are ways for white to go wrong among people who aren't that well booked-up, for example 32% play 9. Bb5 and black scores almost equally well against that. The big problem seems to be finding winning chances for black after ed, which is what all the top players are playing nowadays. Black gets an isolated d-pawn and the winning percentage becomes very low. I've looked at chesstempo at various rating levels also to confirm the results look the same - black's big problem is in getting a win.
Maybe the Scheveningen would be a good option if you would be happy with a draw but don't want your opponent to know that as he might associate playing into the Keres with riskiness trying to win. You could also hope for the opponent to play 9. Bb5 or some similar inaccuracy, as the Scheveningen isn't very popular these days. Of course that would only last for so long if the opening became popular again.
Otherwise we need someone with new ideas on how to create practical winning chances for black, especially in the following position (or 6. ...e5 a completely different way of playing), to try and revive the opening to its former prestige. It hardly looks like a dead draw with best black play, there must be some way.