Grossed out after helping someone cross the road

I was waiting at a traffic crossing at Bugis this afternoon when there was a man who looked to be in his mid-40s struggling. He had this heavy, exaggerated limp and looked like he was having a genuinely hard time keeping his balance. As the green man came on, he looked me at my eye, and desperately signaled for me to help him get across before the light changed. My immediate instinct was he is immobile, so I stepped over and offered him my arm to hold onto.
Instead of taking my arm or resting his hand on my shoulder for balance, he immediately leaned his entire body weight against my side and slid his arm right around my waist. The problem is I was wearing a fairly short, tight-fitting ribbed crop top, and his bare hand was holding on my exposed skin.

I kept trying to subtly shift my body away to guide his hand up to my arm, but his grip just tightened, and his fingers were pressing right into my side. The entire slow walk across the road, he was pressed against me, breathing right near my neck.

I can’t stop blaming myself for my choice of clothes today. If I had just thrown on an oversized t-shirt or a jacket, there wouldn't have been any exposed skin for him to touch. A part of me keeps wondering if he specifically targeted me because of what I was wearing, like my outfit somehow gave him the pretext that I was approachable or easy to take advantage of. I feel so stupid for basically serving myself up on a silver platter just because I wanted to wear something cooling.

The moment we finally reached the other side, I expected him to let go and thank me. Instead, his hand stayed firmly on my waist, and he suddenly flashed this really unsettling smile. He told me he wanted to buy me a meal to "thank me for my kindness," but added that he would need me to physically support him all the way to a restaurant a few blocks down.

That was the moment the alarm bells absolutely deafened me. The vulnerability he was projecting earlier completely vanished from his voice. I immediately pulled myself out of his grip, mumbled an excuse that I was late for an appointment, and basically sprinted away. Looking back, I feel so incredibly taken advantage of. He weaponized my empathy and used a fake disability to grope me in broad daylight.

Pls stay safe and be careful, young girls, take note of creeps that take advantage of your kindness.