What you may not be aware of is how difficult it is to perform certain types of financial transactions without a permanent address. Trading in stocks, for example. Quite often you need to do certain things in person and need to provide identification, which in turn may require a fixed address.

He may have been using the seniors centre as his address, he may have been doing something else.

The key here isn't that he was homeless and used the telephone in the senior's centre, the key is that he was homeless and used the telephone in the senior's centre AND managed an investment portfolio.