Can proof for the resurrection of the dead be proved from this posuk?

(31,16) And Hashem said to Moshe: Behold, you are about to lie with your forefathers, and this people will rise up and stray after the foreign gods of the land into which they are coming, and they will forsake Me and violate My covenant which I have made with them.

The gemara in Sanhedrin 90b says that the Romans asked R. Yehoshua ben Chananiah: From where do we know that the Holy One, Blessed be He, will resurrect the dead and that He knows the future? He replied: Both of them can be learned from this verse - "And Hashem said to Moshe: Behold you are about to lie wih your forefathers and rise up (thus there will be resurrection of the dead); and this people shall stray after the foreign gods (thus Hashem knows the future)". They challenged that perhaps the posuk is to be read "this people will rise and stray"? He replied: You have the answer to half of your question - that He knows the future.

There are several difficulties with this gemara. Firstly, how could they ask if Hashem knows the future when even the prophets foretold the future! Secondly, why did he bring a proof specifically from this posuk? Lastly, what exactly did he mean when he replied that they have the answer to half their question?

But we can explain that their question was based on the difficulty that the Rambam and other earlier Rabbis dealt with, that Hashem's knowing the future and our having freewill are a contradiction to each other. Because if He knows what will happen in the future, how can we have freewill to choose what to do? Conversely, if we have the freewill to choose what to do, how can Hashem know the future? However, Chazal teach that everything is in the hands of Heaven apart from the fear of Heaven, and thus it is not predetermined at the time of conception whether a person will be righteous or wicked. Therefore, their question was only if Hashem knows whether or not a person will sin in the future, because it is not relevant to question Hashem's knowledge of the future concerning everything else since they are in the hands of Heaven.

Now, earlier in the gemara in Sanhedrin it brings a proof for the resurrection of the dead from the posuk in Bamidbar (18,28), which says "and you shall give from it the terumah of Hashem to Aharon the Kohen", which is problematic since Aharon died before they entered Eretz Yisrael where Terumah could have been given to him. Therefore, the posuk must be saying that they will give terumah to Aharon after the resurrection of the dead.

However, since the Romans were questioning whether Hashem knows if a person will sin in the future, R. Yehoshua could not bring a proof to the resurrection of the dead from Aharon, because perhaps Hashem did not know that Aharon would sin by the waters of Merivah, and so He thought that Aharon would enter Eretz Yisrael in his lifetime and be given terumah. Therefore, he brought a proof from our posuk instead. And when they challenged his reading of the posuk he replied that they have at least answered half their question, that He knows the future, because our posuk clearly shows that He knew that they were destined to sin. Thus, the resurrection of the dead can now be proved from Aharon.