The statements you are making now are already retreating from your initial position. "Bringing in drugs and crime" is not equivalent to "every immigrant is a criminal", which was your initial interpretation. I think it's reasonable to disagree with Trump on matters of degree and relevance, but not to wholly twist his statements or rely on divining his state of mind.

One, his statement is not qualified wrt other populations. A strong defense against a similar statement about immigrants in Germany was that the crime level of immigrant populations was of a similar magnitude to natives. Trump's argument could easily be challenged the same way.

The second way would be relevance. It's trivially true that some of the immigrants may bring in crime. Is this important to the discussion? Many decisions have adverse consequences but are still taken as a measure of overall good or moral fortitude. An example would be giving free speech to people with reprehensible ideas - while it may lead to offense and actual harm, it is argued as both a net positive good and a show of moral fortitude, that the societ is secure enough in its beliefs that it ia willing to entertain arguments striking against its core. Similarly, one could argue that Mexican immigrants bring in a net positive(it is a common trope that they are hardworking and willing to take on otherwise undesirable jobs). You could also argue that American society should have(within reason) the fortitude to accept immigrants and give them a chance to integrate and enjoy the benefits of Amercian society.

You don't need to strawman Trump to argue against his rhetoric. By far Trump's strongest political weapon has been to bait people into emotional outrage and theb turn around and use that as ammo.