Icing to increase flexibility?

I stumbled across an article today that seems to go against what I have always understood about stretching and flexibility. I have always been taught that to truly stretch you need to warm up your muscles first. Typically this was done by working the muscles at a lower intensity but I remember a physiotherapist telling me that I could cheat with one particularly stubborn muscle and heat it up with a heating pad or similar first to fit in some extra stretches throughout the day. But the article I found today by Gkrilias et al (2017) looked at the benefits of applying ice to the hamstring before doing a sit and reach test which is a fairly standard test of posterior chain (all the muscles, etc along the back of you including your hamstring). They found that applying ice and applying ice and then stretching both resulted in significant improvements compared to the control, which was sit around for the same amount of time. According to the article improvements after icing are due to the temporary numbing due to the ice.

This leaves me with a whole bunch of unanswered questions. Does the short term improvement lead to any long term improvement? Does this approach increase the risk of injury? Does it affect the elasticity of the muscle? To name a few of them. This is definitely something I need to do more investigation into, particularly given my ongoing battle with my own hamstring flexibility.