He was told, instead, that he'd be going to the Tour of Britain, but any lingering jealousy of his colleagues over in Spain was wiped away on Thursday as the Dutchman smashed the stage 5 time trial to take the overall lead of the race.
In case his team management hadn't got the message from the BinckBank Tour, Boom's superiority over a field that included Tony Martin, Victor Campenaerts, Vasil Kiryienka, Stefan Küng – to name but a few – was an emphatic confirmation of his form.
"I already showed it already in the BinckBank. And now again," said Boom, speaking to the press in Clacton-on-Sea.
"Especially when you see all the names in the top 10, I'm really happy with this. It wasn't perfect because the week before we came to Britain I had some stomach problems, so I was looking for the shape but the feeling is pretty good.
"In the end, I'm happy now that I'm here. I think it's really good preparation for the World Championships in Bergen. If you see the stages we did the last few days, the tempo was really high, the level was high, so this is a really good race for me."
Boom is now in the driving seat to win the Tour of Britain for a second time, having previously triumphed in 2011 – back when, as he admits, the field was nowhere near as strong as it is these days.
He has a lead of eight seconds over teammate Campenaerts, with Kiryienka at nine seconds and the rest of the time triallists in the upper echelons, this being the first decisive GC day after four successive bunch sprints. And at least two of the remaining three stages are set to end in sprints, with the penultimate stage into Cheltenham, with its late climb, the only realistic opportunity for attacks and splits.
If Boom can survive that, the only threat would seem to be Edvald Boasson Hagen, eighth at 19 seconds, whose sprinting form so far this week would suggest that 20 bonus seconds – there are 10, 6 and 4 for the top three places on each stage – is not out of the question.
"We have to make a plan for the next few days. It can be difficult with only six-rider teams, so that makes the racing a bit more tactical, but that's what's quite nice about this race. 20 seconds is not much," said Boom, who pointed out that having a teammate in second place gives LottoNL the strongest hand in that tactical game.
"I think it will change a little bit for the finales now. I was working for [sprinter] Dylan [Groenewegen], so I will try to do my work maybe a little bit earlier, but for sure the focus now is to win the GC on Sunday in Cardiff – I think that's the most important thing now."
Boom also hinted that he might go on the hunt for bonus seconds at the intermediate sprint points, as he did on stage 2.
"I took already a few bonus seconds in the sprints, and maybe that's also a good way to defend the jersey," he said. "If they're almost for free, the bonus seconds, you have to take them. I've been in a lot of stage races like this where the GC ends up in a game of seconds, so it can be really important, I think.
"We have to see if I can hang onto the jersey. But first, we're going to celebrate tonight because we were talking about it for a few days already with Dylan, we wanted to have a beer with dinner, and now we can have one."