I think this section is supposed to invite a reading of anal sex while still working without it. The winks and nudges come further down the page though:

"One had to be strong to bear him. But it took some getting at, the core of the physical jungle, the last and deepest recess of organic shame..."

And right after that, a historical allusions to Greek Vases.

"The same on the Greek vases, everywhere! The refinements of passion, the extravagances of sensuality! And necessary, forever necessary, to burn out false shames and smelt out the heaviest ore of the body into purity. With the fire of sheer sensuality."

There's a lot of other stuff going on in the sex scene regarding the feminine role in sensuality ("giving in") and the sex as a vehicle for transcending both the self and social mores. Adding sodomy only hammers home these points, as it was illegal at the time even between heterosexual couples, and it has historically been viewed as the ultimate submission/receiving act. But the scene also works if you just think they had super animalistic sex.

Apparently, people defending the book in the obscenity trial worried that the prosecution would read the passage as a scene of sodomy, which was still illegal then some 30 years after initial publication:

https://www.theguardian.com/books/2017/nov/21/sodomys-low-profile-in-lady-chatterley-trial