You might want the get the tiniest bit of sense before you type.
If the bill passes and becomes law with that provision in it there is no choice to make. Its the exact same situation as when they passed a bill forcing Boris to ask for an extension, he didn't want to do it but he was forced to send the letter.
The PM doesn't get to pick and chose what laws he will or will not follow.
Additionally, I will say it again. Boris wants a hard brexit. He wants the UK to crash out, mostly likely because he and his donors have bet against the UK economy. That is why he tried to crash out before but was stopped when forced to ask for an extension. That is why the current Brexit bill has the 'no extending past 2020' limit in it. So that when December comes around without a trade deal, which is highly likely due to the time frame, parliament cannot stop him for forcing a hard crash out of the EU.