To be fair Regice is found on Mt.Coronet in Platinum
well...it only appears there if you have the special event regigigas, but yeah it's chamber is around there.
Except the preview has Tsurugi telling Goh he was disqualified.
who's to say he isn't convinced to give Goh a second chance? or it could be a test of character...granted if Goh finds Regice first and deviates from the mission thinking that Regice would net him "bigger points" then yeah he deserves to be disqualified for not following the objective as at that point his "capture everything I see" syndrome would've definitely bit him big time.
Even so...he'll probably come up with some excuse to get back in (Ash likely helping despite Goh's "Solo" mentality...) , like maybe he'll find the alolan ninetales in the end and prove his worthiness despite the rough start.
Cause I don't see why they would've gone through the trouble of bringing up this project if Goh wasn't going to be a part of it (especially after Gary goaded him in), unless the project ends up motivating him into looking for Mew sooner of his own accord since he still wants the thing, but now knowing that others are looking for it, it would force him to change his goal of capturing all other pokemon before Mew, to just gunning for Mew as soon as he sees it because others are looking for it.
honestly if this leads to a few episodes of Goh having a situation similar to what Ash went through after his first match with Bea, I would like that as it would give Goh some deeper character growth, but at the same time if things are resolved by the end of the episode, it wouldn't surprise me either.