Companies 101: It's a legal nicety to prevent problems later. Whilst a Company may have the 'power' to anything it is limited to only doing things that its 'Objects' permit it to do, thus even though the power to do something to the overall benefit of the Company may seem reasonable if it wasn't actually defined under the 'objects' as something that /could/ be done then a shareholder (in this instance a Guarantor member) could, legally, go to law to prevent it happening.
Companies are only allowed to do the things that their Objects permit (ie require) them to do. This is why the final Object for just about every company is of the "do anything else appropriate" form as it covers all the possible bases and stops others preventing it from doing useful stuff. If it isn't an explicit object it effectively doesn't exist.
That makes perfect sense for a non-charitable company. A charity's objects, on the other hand, must be entirely charitable. In order to keep the object charitable, they've restricted it to promoting the other objects, which makes it completely redundant.